906 FOODS AND FOOD ADULTERANTS. 
thorough study until quite recently. The recent investigations and 
discoveries in this line by Dr. Schulze at Ziirich, and Dr. Tollens at 
Gottingen, and their collaborators, have brought about a more careful 
study of the carbohydrates of coffee among a host of other vegetable 
materials. Thanks to their labors, the percentages of compounds in- 
cluded in the term “other non-nitrogenous substances” have already 
been materially lessened in a great many cases. 
Rather indefinite statements about sugar, gum, and aestiide make 
up the existing literature of the carbohydrates of coffee which are 
soluble in water. The coffee berry contains no starch. Mr. Walter 
Maxwell! has demonstrated the presence of an insoluble carbohydrate 
which yields galactose by hydrolysis, and has succeeded in obtaining a 
considerable portion of very pure and well crystallized galactose. RK. 
Reiss”? has reported mannose as an hydrolysis product of an insoluble 
carbohydrate of coffee. 
By investigations made in this laboratory, cane sugar has been shown 
to be the principal soluble carbohydrate present. It is accompanied 
by a small percentage of a substance closely resembling dextrin and some 
reducing sugar. The latter may be due to the inversion of a small 
amount of the cane sugar before or during the process of extraction. 
A considerable amount of cane sugar was obtained in pure, well-defined 
crystals. For the purpose of isolating it from other soluble substances 
of the berry, the extract obtained by the use of 60 to 70 per cent alcohol 
is treated with a slight excess of lead acetate and the excess of the 
latter removed from the filtrate by means of hydrogen sulphide. The 
Sugar is now converted into strontium saccharate by treatment with 
strontium hydroxide at the boiling point of the liquid. The precipitate 
of saccharate is separated by filtration, suspended in water, and de- 
composed by a current of carbon dioxide. The filtrate from the stron- 
tium carbonate thus formed is evaporated to a heavy sirup. This sirup 
is purified by repeated solution in alcohol, reévaporation and resolu- 
tion, gradually increasing the strength of the alcohol. The final solu- 
tion in very strong alcohol is left to crystalize. For this method we 
are indebted to Schulze, Steiger, and Maxwell.’ 
Just as satisfactory a preparation of cane sugar was obtained by the 
evaporation of the filtrate from the precipitated lead sulphide and by 
direct treatment of the residue with alcohol without the use of stron- 
tium hydroxide. A preparation is now in progress without the use of 
either strontium hydroxide or lead acetate, and promises very good re- 
sults, the separation being made by use of alcohol alone. 
The portion of coffee insoluble in water is also being made the sub- 
ject of detailed sry By distillation with yiroehlenc acid an abun- 
1 Unpublished notes. 
2Ber. d. d. chem. Gesell.. 1889, 22, 609. 
3Untersuchung iiber die chemische Zusammensetzung einiger Leguminosensamen. 
Landwirt, Versuchs-Stat., 1891, 39, 269. 
