685 



closely in most cases. The results wbere tlie substance was not (lri( d 

 liclbre extractiou (method 3) were in general somewhat higher than 

 those where it was previously dried (method 2); iu one case this ditt'er- 

 ence amounted to nearly 3 per cent of oleic acid. 



The experiments indicate, in general, that the estimation of free fatty 

 acids in the dried ether extract from materials previously dried does not 

 give a reliable indication of the character of the fat. The absolute con- 

 tent of free fatty acids can only be determined according to methods 3 or 4. 

 A combination of these methods and method 1 may be of value as indi- 

 cating (by the dilference between the results of 1 and 3 or 4) the content of 

 volatile fatty acids, which largely influence the smell, taste, and general 

 elfect of the food upon the animal. Since they are largely products 

 of decomposition by fungous or bacterial growth, their determination 

 furnishes a means for judging of the degree to which a feeding staff 

 has spoiled. The so-found volatile acids calculated to oleic acid should 

 be recalculated for some volatile fatty acid of lower molecular weight, 

 as, ior instance, butyric acid. Otherwise in some cases a larger amount 

 of fatty acids might be found than of total ether extract, as was the 

 case in an analysis of pea-nut meal cited by the authors. 



Xylose, or wood sugar {Landw. Versuchs- Stationen, 38, p. 322). — In the 

 section for agricultural chemistry and experimentation at the meeting 

 of German naturalists, September, 1890, Professor B. Tollens described 

 the preparation, properties, and reactions of xylose, and its occurrence 

 in wood and numerous feeding stuffs. He urged the desirability of 

 taking the xylose into account in the examination of feeding stuffs, and 

 of determiniug its nutritive value. 



Dr. F. Lehmann (Gottingen Experiment Station) stated that he 

 planned to make experiments to determine the digestibility of the 

 gums, the wood gum (giving xylose by inversion) among others. Large 

 quantities of substances giving the furfurol reaction, a characteristic of 

 xylose, arabinose, and substances yielding these sugars, were recog- 

 nized in dried excrement, indicating that these substances pass through 

 the animal without being digested. Experiments in feeding pea-nut 

 cake and woody substance previously treated with sodium hydrate 

 solution (which extracts the wood gum, yielding xylose by inversion 

 with a(!id) showed that the crude cellulose was rendered much more 

 digestible by the removal of this wood gum. 



The gravimetric determination of pentaglucoses in vegetable materials, 

 B. Tollens and G. de Chalmot [Ber. d. d. chcm. Gesell., 24, p. (;i)4).— 

 Tliis is a modilication of the method recently described by Tollens and 

 Giinther.* The material to be examined is distilled in a bath of Rose's 

 metal with IICl of 1.00 si)eciflc gravity, allowing acid of the same 

 strength to replace that distilled over. The furfurol in the distillate is 

 determined not by titration, but by i)recipitation with idienyl-hydrazin 

 acetate. The distillate is neutralized with sodium carbonate, slightly 



•Ber. d. d. jLem. Gesell..23,p. 1751. 



