296 



A. — Examination of the iijiper liquid or of the fatty stratuvi. 



After tlie stratum of fat has so far congealed on cooling as to be 

 removable by a spatula, it is thrown into a ])orcelain dish. Add to 

 it an equal volume of water, warm imtil fused entii-ely, stir 

 assiduously, and keep warm half an hour, let cool, peiforate the 

 hard layer of fat, pour the sul)natant aqueous liquid into the 

 beaker containing the lower aqueous stratum B and the solid mass 

 C, and repeat the operation once more with fresh water, or as 

 often as the water shows an acid reaction. 



Should the fat in ordinary tempeiature or in a cool place prove 

 fluid, or of too soft consistence as to allow its removal by means 

 of the spatula, then the whole mixture — warmed if necessary — is 

 poured into a high, narrow, glass jar. Pour, after the two layers 

 have completely separated, the oil stratum into a })orcelain dish — 

 the last portions of it by means of a pipette — pour back the 

 aqueous liquid into the beaker, mix the oil in the dish with an 

 equal volume of water, warm gently under stii-ring for half an hour, 

 pour back into the jar, separate as before the oil from the water, 

 and re}ieat, should the water exhibit an acid reaction, the opera- 

 tion a third time. 



Now digest the fat, freed from all matters soluble in water, with 

 three times its weight alcohol of 70% (of 0"890 specific gravity), 

 in order to remove any resin present. The result in this case is 

 only approximate, but fortunately the simultaneous occurrence of 

 much fat and of much resin is very rare. Any small portions of 

 resin contained in the fat pass completely into the alcohol of 70%, 

 and traces of fat, dissolved by the latter solvent when hot, 

 se^iarate on cooling. Leave the alcoholic solution in a cold place 

 for one day, filter, decolourise with animal charcoal if necessary, 

 filter again, and bring to dryness at a moderate heat. 



A remnant, obtained hereby, is a resin (or a glucosid), generally 

 in very small quantity; it is to be tested regarding its external 

 characteristics, as fusibility, solubility in benzol, chloroform, wood- 

 s^jirit, sulphide of carbon, petroleum, oil of turpentine, alkalies, 

 and in concentrated mineral acids. If it is a glucosid it will form 

 sugar, when heated with diluted sulphuric acid (1 part acid and 

 1 parts water) for a quarter of an hour, and the presence of sugar 

 in the liquid will be recognised by the reduction of alkaline tar- 

 tarate of copper to red sub-oxyd, when heated together for a short 

 time, and after previous neutralisation Avith carbonate of baryta 

 and filtration. The sugar may also be recognised, and with greater 

 certainty, by its sweet taste, after the acid liquid has been neu- 

 tralised by carbonate of baryta, filtered and evaporated to dryness. 

 In this case the properties of the other product, obtained by the 

 breaking uj) of the glucosid, have also to be determined. 



