392 Intelligence and Miscellanies. 



Potatoes, obtained in the market, contain per hundred 

 weight, Water, - - - - 72 



Ligneous fibre, - - - - 2 



Starch, - - - - 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. 



To 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 the 



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 iOO kilog. of ^oo<Z 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. 

 We 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. 



L'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 

 suflSciently 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 

 well established, otherwise the decomposition is not complete. 

 —Idem. 



