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Owing to accumulations of troublesome deposits on the gas side of tubes in one of the boilers at the Naval Gun Factory in Washington, a thorough study of the formation of the deposits was undertaken. From this work an improved method of analyzing products of combustion for SO2 and SO3 content was developed, details and procedure for which are given in the paper.

It has been determined from extensive laboratory and field tests on the stability of coal suspensions in fuel oil that each installation must be given individual consideration if satisfactory results are to be obtained. However, no particular difficulty in devising equipment or operating routine for efficient use need be experienced. A sufficiently stable suspension of coal in oil for practical purposes can be prepared by dispersing 40 per cent coal by weight ground from 98 to 99 per cent through a 230-mesh screen in heavy fuel oil. Careful control of storage and handling temperatures is required for most successful operation. Combustion efficiency is likely to be slightly less than that of fuel oil. The best opportunity for the successful use of coal-in-oil suspension is in the larger plants with better operating personnel and more readily accessible equipment.

In measuring the temperature of a stream of hot gases surrounded by colder or hotter surfaces, heat radiates to or from the measuring instrument, making it read high or low, and the difference between the true temperature of the gases and that indicated by the instrument is called the radiation error. The paper enumerates the factors with which this error varies, and to show the magnitude of the effects of some of them, gives results of a series of measurements made with thermocouples placed at different points along the paths of gases flowing through water-tube boilers, citing one instance where the error under certain conditions can be as much as 320 deg. cent.

The author discusses the types of spreader stokers in use together with their adaptability for different boiler installations and for burning different grades of fuel. He presents the reasons for their adoption in various Government plants where boilers range in capacity from 100 to 400 hp. The paper contains a table of data showing the results of a number of complete boiler tests conducted on installations equipped with spreader stokers.