resulting lead salt is then found to be free from nitrogen and to have a composition represented by the formula C{6}H{10}O{4}(PO{4}Pb){2}. Lebedeff carries out the preparation in a somewhat different manner. The fermentation is effected by means of air-dried yeast (150 grams to 1 litre of water, 210 grams cane-sugar and 105 grams of a mixture of 2 parts Na{2}HPO{4} and 1 part NaH{2}PO{4}) and the liquid (about 700 c.c.) after boiling and filtering, is treated with an equal volume of acetone. About 300 c.c. of a thick liquid is precipitated and this is redissolved in water and precipitated by an equal volume of acetone two or three times. The final liquid is then precipitated with warm lead acetate solution and filtered and washed with dilute lead acetate solution until the filtrate is clear and no longer reduces Fehling's solution after removal of the lead [1910]. Euler and Fodor [1911] on the other hand precipitate the free phosphate with magnesia mixture and then add acetone, dissolve the syrup thus precipitated in water and add copper [p049] acetate solution. A blue copper salt is precipitated which is thoroughly washed with water and used for the preparation of solutions of the acid. A solution of the free acid can readily be prepared by the action of sulphuretted hydrogen on the lead salt suspended in water. It forms a strongly acid liquid, which requires exactly two equivalents of base for each atom of phosphorus present to render it neutral to phenolphthalein. It decomposes when evaporated, leaving a charred mass containing free phosphoric acid. The acid is slightly optically active, and has [/a/{D}] = + 3·4°. A number of amorphous salts have been prepared by precipitation from a solution of the sodium salt, and of these the silver, barium, and calcium salts have been analysed with results agreeing with the general formula C{6}H{10}O{4}(PO{4}R′{2}){2}. The magnesium, calcium, barium, and manganese salts, which are only sparingly soluble, are all precipitated when their solutions are boiled but re-dissolve on cooling, and this property can be utilised for their purification. The alkali salts have only been obtained as viscid residues. A difference of opinion exists as to the molecular weight and constitution of this substance. Iwanoff [1909, 1] regards it as a triosephosphoric acid, C{3}H{5}O{2}(PO{4}H{2}), basing this view on the preparation of an osazone which melted at 142°, but when recrystallised from benzene gave a product melting at 127°-8°, which had the same appearance, melting-point, and nitrogen content as the triosazone formed by the action of phenylhydrazine on the oxidation products of glycerol. Neither Lebedeff [1909] nor Young could obtain Iwanoff's osazone, and all attempts to reduce the acid with formation of glycerol either by sodium amalgam or hydriodic acid were unsuccessful (Young). There is therefore practically no serious experimental evidence in favour of Iwanoff's view.