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As a result of the studies recorded here, it has been established that the limiting temperatures of the pistons in high-performance diesels, i.e., the highest temperature at which no high-temperature deposits (varnish and carbon deposits) are formed, are as follows: 180†C for D-11 and M-12 oils without additives, 200†C for M-12V and M-14V oils with VNII NP-360 additive, and 256†C for M-14VI and M-14Vts oils with effective additive packages.

— The fluoride release of varnish-coated silicates and liners and sealants was studied by measuring the uptake of the released fluoride by synthetic hydroxyapatite. Silicate specimens were made and coated with cavity varnish. The specimens were shaken in solution with the apatite for 7 weeks. The apatite was analyzed for fluoride each week and the specimens were then transferred to a fresh solution with new apatite. The varnish reduced the fluoride release during the first three weeks, but after that time the release from the varnish-coated specimens was the same as that from the uncoated specimens. The release from the liners and sealants was studied by coating composite resin specimens with the material. The resin contained no fluoride. The specimens were shaken in solution with apatite and the fluoride uptake was measured each week in the same manner as for the silicate specimens. The liners showed an initial release of fluoride. When the two different sealants were applied as two layers, only one of the brands showed initial release of fluoride. Five layers of sealant resulted in an initial release from both brands.

Pigmented films based on different polymers and their blends have been prepared on pine-wood and low-carbon steel substrates, and exposed in laboratory and out-of-doors. In the high humidity cabinet, films based on pentaerythritol alkyd modified with 65% linseed oil and applied to a pine-wood surface, deteriorated by blistering, except those pigmented with titanium dioxide. A blend of the same medium with stabilized chlorinated rubber showed good resistance to degradation in high humidity conditions as well as in marine and industrial environments. In the latter system, especially the combined pigmentations zinc oxide/rutile behaved very well on aging. However, in linseed oil varnish, the combined pigmentation zinc oxide/rutile/basic lead carbonate protected the exposed films very well. The rutile modification of titanium dioxide protects a polymeric film by absorbing ultraviolet light which would otherwise damage it. Also, zinc oxide indicates complete absorption of the shorter wavelengths, and basic lead carbonate transmits much more ultraviolet light. Nevertheless, lead and zinc soap formation with free acids might affect various film properties in the above pigment combination. The highest retention of whiteness was exhibited by the film samples exposed to a marine environment, and the lowest by those exposed to an industrial atmosphere.

The economic efficiency of the coating with the higher initial cost is explained by the fact that the total expenditures for corrosion protection depend on the complexity, volume, and cost of concomitant operations, mainly, on the frequency of necessary restoration of the coatings. The more difficult it is to accomplish these operations and consequently the higher their cost, the more advantageous it is to use the more durable, although more expensive material. When selecting protective materials one should take into account not only the conditions under which the mechanical equipment operates but also the conditions of performing operations on the repair and restoration of the destroyed protective coating, and one should select from the recommended materials and schemes of coatings those which provide a reduction in expenditures for corrosion protection of equipment for a prescribed service life.

The author describes a method for making nitrocellulose replicas of the surface of metal parts for use in microscopic examinations of the state of the surface. Surface preparation is discussed for both macrographic examination and micrographic examination. Application of the nitrocellulose varnish and removal of the completed replica is explained and the author concludes with examples of some of the applications of this technique.

The marginal adaptation of dental restorations placed in extracted teeth was studied by means of a tracer method utilizing Ca 45 . The following observations were made: 1.There was no difference in the sealing ability of inlays cemented with zinc phosphate, resin, or zinc oxide-eugenol cements. All restorations exhibited good adaptation initially, with a slight increase in marginal leakage occurring with time. 2.The sealing qualities of zinc oxide-eugenol cement were initially much superior to those of gutta-percha. 3.The adaptation of amalgam restorations was not appreciably altered by expansion or contraction of the alloy during setting, since the leakage patterns of grossly expanding and contracting alloys were comparable. Initial leakage of restorations placed with both alloys was virtually eliminated by the use of a cavity varnish. 4.The best adaptation of resin restorations to cavity walls was attained through use of a combination flow-bulk pack technique, while restorations inserted with the flow technique were superior to those placed by the bulk pack procedure. No difference was discernible in the adaptation of resin restorations which were finished 15 minutes after placement and those on which the finishing procedure was delayed for 20 hours. 5.Marginal leakage of silicate restorations was reduced by use of a cavity varnish. Silicate restorations finished immediately after removal of the matrix exhibited more leakage than those finished after 24 hours.

Acoustical effects of violin varnish—those of mass, stiffness, and internal friction—are examined qualitatively and quantitatively. Dynamic measurements of Young's modulus, real and imaginary, are made for films of typical oil varnishes on a substrate of cross‐grain spruce through aging periods of 1 yr or more and expressed in the practically useful terms of modulus over density. After 112 yr, the hard varnish had a real modulus per unit density of 2.5 × 1010 cm2/sec2 and Q about 23; after 1 yr, the values for the soft varnish were 1.6 × 1010 and 8. A high‐grade floor varnish had intermediate values. The imaginary component of the soft one was substantially independent of frequency from 400 to 5600 cps. Exact calculations of added loss and tuning shift, made for a “pseudofiddle” comprising rectangular top and back of orthotropic materials simulating spruce and maple, are believed roughly representative of the violin. Added loss is more apt to be damaging than is detuning of plates. The loss comprises two ...

Thorium-X, a solid substance, or rather its compounds (oxide, nitrate, etc.) can be dissolved in water, alcohol, varnish, etc., and mixed with ointment, incorporated in plasters, or applied with bandages. In 1912 it was only available in water solutions or in saline. This, however, made external application for skin diseases difficult. I therefore asked the Auer-Gesellschaft to supply an alcoholic solution for the external application on which I reported in 1916 (Nagelschmidt, 1916). The use of normal saline or water for intravenous application or per os was kept up. The propyl-alcohol solution,* made on my request, dries quickly on the skin. It allows of a certain degree of dosage; on spots where we desire to produce a light effect we may use a single coat; on others, for a more intense effect, we may apply two, three, or more coats (maximum five in severe cases). After drying I used to cover the thorium coats with mastic in order to fix it safely and to dispense with bandaging, especially in the face an...

The purpose of this study was to test the influence of cavity liners, under class V silver amalgam restorations, on the penetration of radioactive tracers through the filling margins and the underlying dentine. Two hundred and thirty-four newly extracted human teeth were used in this study. Eight different liners and bases were tested in four different isotope solutions. It was found that the films formed by a copal resin varnish and a polystyreneethylcellulose liner prevented dentine penetration of the isotopes via the filling margins and also decreased marginal penetration significantly. The calcium hydroxide liners completely blocked dentine penetration by the isotopes but tended to concentrate the radioactive solutions in the liner substance. Marginal penetration was slightly increased. Zinc oxide-eugenol bases decreased dentine penetration somewhat but did not decrease the degree of marginal penetration. Zinc phosphate cement increased dentine penetration markedly as well as penetration of negative ions into the amalgam substance. Marginal penetration also may have been slightly increased. Under the conditions of this experiment, copal resin varnish, polystyrene-ethylcellulose liner, and calcium hydroxide liners were effective in preventing penetration of radioactive ions into the dentine and pulp; zinc oxide-eugenol and zinc phosphate cement bases were not.

A method for evaluating the thermal stability of magnet wire enamel has been developed using the dielectric strength of the enamel film as a criterion. This test method was designed for accuracy, simplicity, and economy in time, labor, materials, and equipment. Standard National Electrical Manufacturers Association (NEMA) dielectric strength twists1 are dipped in an electrical impregnating varnish and used as test samples. To achieve sufficient accuracy, a large number of these twists are included in an enamel evaluation program. The twists are placed in aging ovens at various temperatures. Periodically the samples are removed and tested by applying a high voltage. The average aging time required to reduce the dielectric strength of the twists to a preselected value is considered the life of the enamel. The relative life of the enameled wire insulation system over a wide temperature range may then be predicted from the life of the samples determined at several temperatures. Studies have been made of this test method under different sample preparation methods, failure criteria, and aging conditions. Results determined by this test are compared with motor-aging test results on the same enamel-impregnating varnish insulation systems. This comparison shows that this is a convenient functional test method that can be correlated with the results of a more complicated motor test program.

Bei der Untersuchung der Lacke ermoglicht die Kombination von Gas-Chromatographie und Pyrolyse sowohl eine Aussage uber die fluchtigen als auch uber die schwerfluchtigen und festen Bestandteile der Lacke. Diese kann zur Qualitatsbeurteilung der Produkte verwendet werden. About the Possibility of the Use of Gas Chromatography in the Paint and Varnish Industry By the examination of varnishes with the combination of gas chromatography and pyrolysis, it is possible to tell about the volatile as well about the difficultly volatile and solid components of the varnish. This can be used to determine the quality of the product.

Three good methods of marking bees are, the use of a thick oil paint (artist's colors); powdered pigment, white shellac and alcohol; and a varnish enamel. The most satisfactory one is the use of one part dry pigment mixed with one part liquid white shellac and diluted to the right consistency with ethyl alcohol.

A survey is made of sampling systems used in gas chromatography. The application of a sampling device for gas chromatographic analysis of volatiles in polymers based on the principle of breaking off the tips of glass ampoules is described. The possibilities are discussed of the multipurpose application of this device as a sampling device for heterogeneous systems and as a microreactor for various chemical reactions with subsequent analysis of the volatile products. Examples are given of the application of the device in the study of polyethylene cross-linking, in analyzing the decomposition products of peroxides, for the determination fo volatiles in butadiene—styrene paper-based laminates, for following polyesterimide varnish curing and for the identification of polymers by the analysis of low-molecular-weight pyrolysis products.

have been used by man throughout the ages to serve his purposes in waterproofing or preserving many things. It is reputed that Noah's Ark was calked with pitch. The reed basket in which Moses was hidden was daubed with pitch to make it waterproof so that it would serve as a small boat. It is probable that Noah used vegetable pitch such as exudes from pine and fir trees, but asphaltic mineral pitches were known to the Egyptians and were put to many uses, including the preservation of mummies. The use of pitch for corrosion prevention brings us to relatively modern times. Early cast-iron pipes for water works were not coated in any way. It is probable that troubles from the products of corrosion first indicated the need of a lining. About 90 years ago, then, pipe was first dipped in coal-tar varnish (1) to prevent tuberculation on the inside, the coating on the outside improving its appearance. Bituminous pitches used for modern pipe lining and coating are often thought of as minerals out of the ground, but all are of organic origin. Many forms of asphalt have, in the past, been used, compounded and blended to various formulas. Among these were Gilsonite, Trinidad asphalt, and petroleum asphalt. In many places, local oil seepages supplied pitch of a consistency that required little or no heating for application by daubing. Such material was used in Los Angeles in the 1870 's on sheet-iron pipe. The usual method of application, however, was dipping in a trough of melted asphalt. This permitted the application of relatively uniform linings inside pipe of any size, as well as coating the outside. Coal-tar varnish has long been used as a dip for cast-iron pipe. It has usually been indifferently specified and carelessly handled in the

Studies were made on the causes of defects in underglaze decalcomania transfer on vitreous hotel chinaware. The best hardening-on firing schedule to eliminate frizzling was as follows: (1) Heat as rapidly as ware will permit to 600°F., (2) at 600° to 800°F., heat at rate not exceeding 40° to 50°F. per hour, and (3) above 800 °F., heat as rapidly as ware will permit. The hardening-on fire can be eliminated by reducing the coating of varnish through control of the viscosity of the varnish in the range of 4.0 to 6.0 (Mac-Michael viscosimeter with No. 30 B & S wire, with cup rotating at 19 r.p.m.). The best results on the tackiness period were obtained in a room at 74 °F. dry bulb and 73% relative humidity.

The interaction of varnish with magnet wire enamel can lead to a reduction in the thermal life rating of the insulation system (ASTM D2307-64T). The recognition of this reduction in life rating is encountered first by varnished twisted pairs of enameled wire. An attempt is made to determine the mechanism of this interaction by studying the system microscopically, by differential thermal analysis and by infrared analysis. The microscopic analysis defines the nature of the bond between magnet wires and the type of coverage that the varnish gives to the magnet wire. It also reveals some information on the type of attack on the enamel and varnish system. Thermal analysis and infrared analysis are used to determine, if possible, whether the thermal decomposition of the magnet wire enamel is accelerated by the presence of the varnish and to reveal some background information as to the nature of this accelerated decomposition. This can then act as guide for the selection of varnishes with enamels that will minimize interactions that reduce the thermal life of insulation.

Desert varnish samples from Deep Springs Valley and Death Valley in California were studied with the use of the electron microprobe. Varnish can be interpreted as having two layers, an inner subordinate layer rich in $SiO_{2}$ and usually $Al_{2}O_{3}$ and an outer main layer rich in FeO and MnO. The subordinate layer may be altered rock which has lost all evidence of crystal structure and to which Fe and Mn have been added. These layers are not distinguishable optically. In varnish on quartzites, FeO, MnO, $Al_{2}O_{3}$, and $K_{2}O$ all increase in concentration outward through the varnish from the rock-varnish contact. However, in varnish on argillites, $Al_{2}O_{3}, K_{2}O$, and sometimes FeO decrease in concentration outward. Comparison of these variations with data on the bulk composition of the fresh rock suggests that elements which increase outward may be supplied largely from external sources and that elements which decrease outward may be supplied predominantly from the underlying rock. The FeO...

With mild agitation, soybean oil is not appreciably contaminated by contact with clean steel surfaces unless the fatty acid content is above 0.1% and the temperature above 150°C. It has been shown that an oxidized oil film is an effective coating for metals used in the construction of pilot-plant deodorizers. Such a film, to be most effective, should be washed free of unoxidized, noncoherent oil with a suitable solvent. If the metal is properly coated an oxidation-stable and flavor-stable oil can be obtained from the deodorizer, providing the oil has been properly refined and bleached. The oil film is nearly the equivalent of a glass surface in its effect on oil stability, is easily formed on a metallic surface, and can be readily removed when the metal is cleaned with caustic. A silicone varnish film baked on the metal surface is somewhat less effective than an oil film. Other methods of treating steel or stainless steel, which include coating the metal with a polymeric ether-linked wax, grit-polishing, and electropolishing, are fairly effective in reducing corrosion of the metal during deodorization.

The double portrait was painted in oil on very thin linen canvas, which in the course of time had become exceedingly brittle. There was the usual accumulation of grime and discolored varnish as well as a large cross-like tear. This puncture was probably the reason for its having been mounted to a rigid backing of 'Masonite' with a white-lead adhesive. The Masonite had been attached with the white

The penetration of varnishes and inks into supercalendered paper under pressure was studied by means of reflectance measurements. The penetration appeared to be proportional to the square root of the ratio of the magnitude and duration of the applied pressure to the viscosity. This relationship is in agreement with the classical physical law for the viscous flow of fluid into a porous medium. It is also concluded that for the systems studied the ink penetrates, under the applied pressure, as a homogeneous body into the paper with no filtration of pigments from the carrying varnish.

FABRICATED, compounded, and formulated goods keep increasing—with plastics' production continuing to show the way, reflecting phenomenal increases over the past decade. The over-all picture continues strong. Coatings plod along and head for another record. Man-made fibers positions are stronger than ever. New rubber consumption is up for the first half of 1957. Protective coatings share the limelight with plastics. Barring unforeseen complications in the second half, 1957 will be another record year for the paint industry—although only by a hair over 1956. Total paint, varnish, and lacquer sales are forecast to exceed $1.60 billion, according to the National Paint, Varnish, and Lacquer Association. This compares with last year's record $1.58 billion, and $1.36 billion in 1955. Industry sales lagged badly during the first quarter of 1957, mainly because of inclement weather conditions. However, sales perked up strongly in April, with turnover setting an April sales record. May sales zoomed, setting an ...

Although the use of tannin for the treatment of water to protect steam boilers from corrosion had been suggested for more than a half century, the first use of antirust protection outside this field was in 1930. A renewed interest in this process occurred when nonarchaelogical objects buried in a medium containing substances of a tannic nature were found to be remarkably well preserved. There are two principal types of tannins, hydrolyzable and con densed. The potential oxidation of the phenolic groups of both types makes them strong antioxidants. Their phenol and carboxyl groups form complexes with metals. Tannification of iron does not spoil other materials in the presence of the iron, such as wood. Tannin solutions can be used to conserve objects with a light rust. The rust is converted by the process and the subsequent drying to strong and resistant layers, connected with the metal base. These form a suitable pretreatment for the application of varnish or coatingsTannin may also be used on objects with thick layers of rust, which are thus converted to a powdery material easily removable mechanically, while a tannate film of suitable protective qualities forms directly on the metal. Describes application with a brush of tannin solutions, as well as the ripening process of the tannate layer. For objects lightly rusted a solution of 200 g tannin in 1 liter of distilled water plus 150 milliliters of alcohol is suggested. To treat objects more heavily rusted it is necessary to add phosphoric acid to the first coat.

Reliable hermetic refrigeration systems require the use of trouble-free motors since there is no opportunity for motor replacement or repair during the operating life of the unit. The hermetic motor is sealed into the system and is exposed to lubricating oil and refrigerant and this environment places special demands on the insulation materials. The ground insulation, wire enamels and varnishes which are used must withstand the physical, electrical, chemical and thermal stresses in the operating environment. In addition to retaining their functional properties, the insulation materials must not be a source of contaminants to the other components in the system.1, 2

Abhangigkeit der Rostbildung vom Klima, der Anwesenheit von Elektrolyten und der Art des Eisens — Walzzunder verringert die Haltbarkeit von Schutzanstrichen und sollte entfernt werden — Handentrostung ist meist unzureichend und sollte bei Neukonstruktionen nicht angewandt werden. — Grobe Sandstrahlung hinterlasst Spitzen, welche Ansatz zur Rostbildung geben, deshalb relativ fein strahlen — Flammentrostung in Verbindung mit Grundanstrich auf noch warme Eisen ist vorteilhaft — Chemische Entrostung und Rostumwandlung bei Stahlbauten nicht bewahrt — Washprimer und Spritzverzinkung — Wirkung der Feuchtigkeit und aggressiver Atmosphare bei der Ausfuhrung von Anstrichen — Bedeutung der Filmdicke — Schema der wichtigsten Bindemittel fur Rostschutzfarben — Die Olbindemittel, Leinofirnis, Standol, Holzol — Art und Wirkung der Pigmente — Bleimennige und Bleicyanamidgrundfarben — Alkydharzfarben und Ol-Alkyd-Kombindationsfarben — Chlorkautschukfarben, Chlorkautschuk-Ol-Kombinationen und Chlorkautschuk-Alkyd-Kombinationen — Bituminose Rostschutzfarben auf der Grundlage von Asphalt — Bitumen und Steinkohlenteerpech — Teerpech-Emulsionen — Vorschlage fu die Wahl der je nach Anwendungsgebiet geeigneten Rostschutzfarben. The Protection of Steel Constructional Work from Corrosion Dependence of the formation of rust on climate, presence of electrolytes and the type of steel used — Mill scale diminishes the life of protective coatings and should therefore be removed — Chipping and other manual methods of scale removal are usually insufficient and should not be used on new constructional work — Sand blasting with coarse sand leaves points on the surface of the metal which facilitate the formation of rust, hence, only relatively fine sand should be used for this purpose — Flame descaling with a primer applied to the warm surface is advantageous — Removal or conversion of rust by chemical means has not proved successful in the case of steel constructional work — Wash primer and spray galvanizing — Effect of moisture and the chemical action of the ambient atmosphere on the application of protective coatings — Importance of the thickness of the film of the coating — Summary of the more important binders for use with anti-corrosive paints (oil binders, linseed varnish, hot linseed oil, wood oil) — Action and effect of pigments — Red lead and lead — cyanamide primary colours — Alkyd resin paints and oil-alkyd paints — Chlorinated rubber paints, chlorinated rubber-oil combinations and chlorinated rubber-alkyd combinations — Bituminous anti-corrosive paints on primers of asphalt, bituminous and coal tar pitch — Tar pitch emulsions - Suggestions for the choice of suitable anti-corrosive paints.

The effect of a cavity varnish on the retention of restorations was investigated by measuring the force needed to push restorations out of bottomless ivory cavities. The varnish lining decreased the retaining force of inlays by half, and slightly increased the retaining force of amalgam restorations.

The physical conditions of varnish drying and the equipment and operating methods of varnish driers are discussed. Furtheron the paper deals with the varnish drying control and he testing instruments used for it. In order to yield a satifactory result the varnish driers must answer the followingsrequirements: they must maintain a specified climate, thus keeping a certain equilibrium moisture content in the wood and guarantee a regular drying on all sides of the object. By right adjustment to the kind and the thickness of varnish the drying time can be reduced to only a few hours. The advantages are a shortening of the passage time, saving of space and often an increase in quality. *** DIRECT SUPPORT *** A02R4139 00002

LAMINATED material from which non‐metallic bearings and gears are fabricated may consist of fabric or paper treated with a synthetic resin. In producing this material, rolls of paper or fabric are fed in at one end of an impregnator which imparts a coating of the resin varnish. The impregnated material is dried and cut into suitably sized sheets, which are placed in layers to form a block of the material. The block is next pressed by hydraulic pressure under heat. This causes the resin to soften and flow so that the paper or fabric laminations merge under the pressure, which is round about one ton per sq. in. As heating is continued, however, the resin sets and can no longer be affected by heat; the laminations lose their separate identity and the material becomes a homogeneous mass. Another type of material much in use consists of asbestos—which may or may not be in the form of asbestos cloth—likewise impregnated with synthetic resin.

In the composite insulation system of a magnet-wire coating and a varnish, there is the possibility of harmful reaction between the two at elevated temperatures. Thus, there may be discontinuities in the Arrhenius curves (log of thermal life versus the reciprocal of the absolute temperature). Experimental results are given showing reactions between certain varnishes and certain combinations of polyester/polyamide-imide enamel systems.

Various mixtures were obtained by mixing cotton seed oil with oleic acid, and solid fatty acid and higher unsaturated fatty acid, both of which had been separated from tuna oil, in varying proportion. Each mixture was put in a lacquered tuna can and underwent ordinary canning processes such as sealing, heating, etc. Two weeks afterwards each can was opened and the conditions of the inside varnish were examined. Of the mixtures, those which have acid value more than 2•5 always caused falling off of the varnish to some extent. But those with acid value less than 1•4 kept the varnish intact.

The rheological characteristics under steady shear flow of dispersions of pigment in a mid-litho oil varnish have been examined. Using a Weissenberg rheogonio-meter the influence of pigment concentration and dispersion temperature on flow behaviour have been examined in some detail. Data have been examined in terms of the initial peak stresses and of the equilibrium stresses encountered. By taking the ratio of these two as a measure of thixotropy it would appear that thixotropy goes through a maximum with increasing pigment concentration. The results also indicate that particle/particle interaction controls flow up to the point at which a peak stress occurs. Thereafter the flocculation/deflocculation process predominates.

The preparation of polyurethane foams or film and varnish coatings from multi-component reaction systems sometimes necessitates selective monitoring of the individual stages in the reaction depending on the technological nature of the process. Accordingly various additives are introduced into the reaction mixtures to accelerate or inhibit the interaction of aocyanates with certain compounds having a labile hydrogen atom. Information has been published regarding the way in which a mixture of amine and organotin catalysts led to the discovery of the synergetic effect during the interaction of isocyanates with alcohols and water [1,2]. The reaction of phenylisocyanate with n-butyl alcohol in the presence of a mixed catalyst took place at a much higher rate than would have been expected in view of the rates of these reactions in the presence of each of the catalysts used by itself.

In connection with a study of various kinds of vulcanized rubber, including rubber films from vulcanized latex and latex films vulcanized in the dry state, it seemed desirable to investigate the packing of the latex particles. To what extent, for example, are these still present or are they coalesced? It is known that the diffusion of water vapor through solid substances may give an indication of the internal structure of matter. With this in mind, a search was made for a simple method to determine the diffusion of water vapor through rubber; high accuracy was not required so much as were simplicity and adaptability to a long series of experiments. Such a procedure was found in the method described by Hoekstra for determining the permeability of varnish films to water vapor. A detailed description of the method is given later in this paper. More accurate methods of determination, applied to rubber, have previously been described by others, but these procedures are less suitable for systematic tests.

Paintings are composed of several layers of various materials. These layers are exposed to outside influences in diverse degrees of intensity depending on their position within the complex structure of the painting. Each layer has its own characteristics which in a well designed paint film have the function of protecting each other from outside influences and their resulting reactions. Thus, the support protects the paint film from the effects of gravity and impact, the sizing protects the priming from the absorbing tendencies of the support, and the priming isolates the paint film from the roughness and color of support. The same analysis can be made starting from the varnish in its protection of the paint film from dirt and atmospheric influences, etc. All these layers are held together by acting adhesive components. Their action and reaction to outside influences is modified by fillers and pigments and other additives. Time and other outside influences change the characteristics of these layers and their effective interlayer adhesives so that they sometimes become unable to further withstand outside stress or stresses caused by divergent reactions of the different layers to outside stresses. The connection between or within the layers breaks, permitting delamination and cracks. The conservators' solution to this problem had been to introduce additional adhesive material into the painting either by local treatment of the affected parts or by impregnation of the whole painting (1, 2). When we see such a painting which has been treated some time ago (usually at a time now undeterminable) we notice deterioration. Is this deterioration due to the treatment, or does it simply show the effects of age? Is it partly caused by the adhesive or possibly by the heat at application? Similar questions can be asked about the cracks. If there existed some machine capable of making time run faster before our eyes so that we could see the effects of age on one part of a homogeneous paint film while keeping another for control, we might be able to answer some of these questions. Attempts in this direction have been made with artificially accelerated aging. However, the aging properties of paint films are so complicated that no satisfactory means of reproducing them

Recent advances in the theory of the intrinsic electric strength of solids are briefly discussed. Methods for the preparation and testing of samples of baking insulating varnishes and shellac-varnish films for the determination of their intrinsic electric strength are described and the results of such determinations, made on a thickness range of 0.02 mm. to 0.1 mm. and a temperature range of ?196° C. are reported. The investigation has also included subsidiary tests, such as conductivity measurements, effect of different ambient conditions (immersion media and applied pressure), time/voltage tests, and the effect of centrifuging and filtering and comparison tests on varnish-impregnated paper films, which were made to establish the validity of the method of test and to assist interpretation of the results. The large and continuous increase of intrinsic electric strength with decrease of temperature down to ?196° C. which is found, disposes of the assumption hitherto made by some investigators that intrinsic electric breakdown is independent of temperature. Consideration of the results in relation to the recent theory proposed by Frohlich to account for a temperature-dependence of the character obtained, indicates that this theory in its present form is not applicable, but an alternative explanation is suggested.

Two techniques of radiography by means of secondary photoelectrons liberated by hard x‐rays (180 kv), one by reflection and one by transmission, are described. Special fine‐grained photographic emulsions of the Lippmann type are required which will not be affected by x‐rays traversing the film, but are sensitive to photoelectrons liberated from the surface of a specimen in intimate contact with the photographic film or paper. In this way photographic negatives may be reproduced (from the silver of the image), microradiographs prepared by enlargement of any area of the radiograph, surface topography studied, ores analyzed, etc. For electronic radiography by transmission, instead of the specimen being its own electron generator, a thin metal foil (usually lead) pressed against the specimen generates the electrons which then traverse the thin specimens, and register on the photographic film or paper. Applications are papers, insect wings, varnish or rubber films, plant leaves, tissue sections, plastics, and alloys.