The potash method of clearing specimens for bone studies has been in use for some time. This method is particularly valuable in studies of bone development or in determining the relation of nutrition to bone structure. The relation of the bones to one another and, also, finer details, can be seen better by this method than is possible by dissection. One disturbing factor is that the large amount of fat in most specimens obscures vision to such an exte'nt that little can be seen in some regions. No solvent has been found effective in eliminating the masses formed by the combination of the potash with the fat (Strong, 1925). Regarding the extraction of fat from specimens prior to clearing with potash, Dawson (1926) states that leaving the specimens in acetone for a considerable period after fixation in 95 percent alcohol is the most satisfactory method. However, we have found from experience that this method is not entirely satisfactory. All the fat is not removed from larger specimens and there is considerable waste of the solvent, due to frequent changing. For these reasons an apparatus which keeps the specimens in a purified solvent is desirable, and one of this type is described. The effectiveness of various solvents in removing the fat from specimens is also reported. The apparatus keeps the specimens in a purified solvent by continuous distillation and intermittent siphoning (fig. 1). The solvent in a pyrex flask (A) is boiled in a steam bath (B). The vapor passes up the tube and is condensed in the condenser (C). The extraction cup (D) is made by cutting the bottom from a large round bottle. A tin lid (E) covers the cup and is packed with cloth around the edges (G). A stopper (F) over the lower end of the condenser, fits closely against the lid to prevent escape of the solvent. A piece of screen wire (H) is placed in the bottom of the cup to prevent specimens from stopping up the siphon tube. The cork (J), through which the siphon tube passes, is sealed with gelatin glue. The siphon tube is flattened at (K) so that the surface tension of the liquid will start the siphoning action. Otherwise there is a tendency for the solvent merely to trickle over. The solvent should siphon over every 20 to 60 minutes. The following method has been followed in preparing the specimen for clearing. Immediately after killing, the hair is removed with sodium sulfide. The specimen is fixed in 95 percent alcohol for at least 3 days. If trichlorethylene,2 alone or in a mixture, is used as a solvent, it is necessary to dehydrate the specimens before extracting the fat, because water and trichlorethylene do not mix. The fat is extracted by the method of continuous purification of the solvent for five days. In case ether or trichlorethylene, alone