384 Messrs. Wanklyn and Cooper on the Determination 



have made a special adaptation of the well-known ammonia 

 process of water-analysis to the case of vegetable proteine. 



The working details of our process are as follows : — 



Into a litre flask a carefully weighed gramme of the ve- 

 getable substance to be analyzed is placed, and 20 cub. centims. 

 of decinormal solution of caustic potash is added, and then 

 water is added until the litre-mark is reached by the level of 

 the liquid. The contents of the flask are then shaken up so 

 as to ensure thorough mixture. In this manner we obtain a 

 liquid of such a strength that each cubic centim. contains 1 

 milligramme of the flour or other vegetable substance to be 

 operated upon. 10 or 20 cub. centims. of this liquid (i. e. 10 

 or 20 milligrammes of the vegetable substance) are conve- 

 nient quantities to work with. 



The next step is to get the retort in order as for a water- 

 analysis, and to place in it 300 or 500 cub. centims. of good 

 drinking-water, and to add 50 cub. centims. of a solution con- 

 taining 10 grms. of potash and 0*4 grm. of permanganate of 

 potash (such as is used in water-analysis), and to distil until 

 the residue in the retort no longer yields the slightest trace 

 of ammonia. That having been done, 10 or 20 cub. centims. 

 of the liquid containing the vegetable substance are to be 

 added and the distillation proceeded with. The vegetable 

 substance will then be attacked, and its proteine will yield 

 ammonia, wLich will distil over and may be measured by 

 means of the Nessler tests. For further details of the man- 

 ner of carrying out work of this description we would refer 

 to the Treatise on Water-analysis, which is now sufficiently 

 well known to chemists. 



It was shown some years ago that egg-albumen yields about 

 one tenth of its weight of ammonia when submitted to such 

 a process as the above, and that solutions containing different 

 quantities of egg-albumen yield ammonia exactly propor- 

 tional in amount to the strength of the solutions of albumen. 

 Our experiments warrant a parallel statement in the case of 

 vegetable proteine ; and in the Table about to be given, the 

 ammonia, multiplied by 10, gives a fair approximation to the 

 actual quantity of vegetable proteine in the different samples. 



As will be observed, our experiments include many descrip- 

 tions of wheaten, pea-, rice-, maize-flour, oats, barley, malt, 

 rye, and arrowroot. The last-named is important as showing 

 a very small proportion of proteine. 



The pea-flour was ground from the peas in our own labora- 

 tory, and passed through a very fine sieve. The rice-flour was 

 likewise of home-manufacture ; and the same is true of maize 

 and the malt. The rest were not powdered in the laboratory. 



Samples of wheaten flour : — 



