392 Intelligence and Miscelianies. 
Potatoes, obtained in the market, contain per hundred 
weight, Water, - - - : 72 
Ligneous fibre, - : - - 2 
S - - - 26 
100 
To bring potatoes to a near equality with wheat flour, in 
relation to bread, there must therefore be added to 100 parts 
of potatoe flour, 4.63 of animal, and 1.53 of saccharine mat- 
ter. In mixing these three substances, we should evidently 
obtain a flour as nutritive, and as easy to be converted into 
bread, as the flour of grain. 
o prepare 100 kilogrammes of animalized potatoe flour, 
take 264 kilogrammes of potatoes, worth - 4.95 francs. 
Coal for dressing these potatoes by steam, 66 
12 kilogrammes of gelatine, - - - 12,00 
4 kilogrammes of grape, or other sugar, - 2.00 
Manual labor in cooking and mixing 
materials, - . - - 4,00 
Add one tenth for all other expenses, - 2.36 
: | 25.97 or 26 fr. 
This mixture rises like wheat flour, and makes good bread. 
The cost of 100 kilog. of good wheat bread at Paris, is 60 
franks, and it appears that the same quantity of animalized 
potatoe bread can be made for. less than one half that sum. 
e shall give in the next number of our Journal, a note 
explanatory of the process employed by M. Darcet, in ex- 
tracting gelatine from bones with facility and economy. 
I’ Industriel Fev, 1829. 
48. Means of detecting the purity of chromate of potash. 
Add to the sample to be tried, a great excess of tartaric acid. 
The chromate is immediately decomposed, and the liquid 
acquires, in the course of ten minutes, a deep amethystine 
color, and then no longer forms a precipitate with nitrate of 
barytes, or nitrate of silver, when the chromate of potash is 
pure ; while these reagents will indicate the slightest traces 
of sulphate or hydro-chlorate contained in the liquid. A ne- 
cessary precaution is to have the solution of the chromate 
sufficiently diluted not to precipitate tartrate of potash, which 
it will do if not diluted with sixty parts of water at least ; and 
the solution cannot be assayed until the amethystine hue is 
llestablished, otherwise the d ition is not complete. 
aN t 
