PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 623 



Mr. Bartlett. — A patent has lately been taken out in Belgium 

 for an improvement in making steel, which consists essentially in 

 passing ammonia over the iron to purify it and make a way for 

 the carbon and nitrogen to enter in. The iron is purified, as 

 they say, by the decomposition of the ammonia which forms a 

 sulphide of hydrogen, by separating sulphur from the iron. 



Mr. Enos Stevens. — Vegetables derive their nourishment both 

 from inorganic and from disorganized substances. Animals, on 

 the contrary, make all of their growth from what has been elab- 

 orated either in vegetables or in other animals. When disorgan- 

 ization has commenced, an article is destroyed for animal food. 

 Burned hay, for instance, is so spoiled as not to be digestible. 

 The system can get rid of food which has been injured by fer- 

 mentation or burning, or by the addition of an alkali, but. such 

 food does not nourish the system. If a cow is fed upon city gar- 

 bage, nature may use it temporarily, but unless something better 

 is soon given to take its place, it will be burned out by fever, 

 diarrhosa, diabetes, &c. And we may expect similar results from 

 the use of improper food by man. A proper system of cooking 

 would make digestion what it should be, a mechanical rather 

 than a .chemical process. We should never use a temperature 

 higher than 200 deg. or 210 deg. If we use a higher temperature 

 than 200 deg., to save time in cooking, we shall lose some of the 

 more volatile elements, and especially the ammonia, and our food 

 will be less nutritive. The proper way is to put one kettle within 

 another, as in the farina boiler, or to let steam play around and 

 upon the articles to be cooked, according to the manner in which 

 you wish the article to be cooked. 



Mr. Fisher. — How would it answer to cook at a higher tempe- 

 rature, taking precautions to prevent the escape of the ammonia, 

 as in Papin's Digester ? 



Mr. Stevens. — That would not do, because there would be so 

 much of the material disorganized. The idea is to retain ev^ry 

 particle, in the state of organization in which it was in the ani- 

 mal or vegetable in which it grew. 



The Chairman. — How would you boil potatoes, &c., for stock? 



Mr. Stevens. — By putting them in a large vat and introducing 

 steam. Practically, it will 'seldom go above 200 deg. 



Mr. Bliss. — In cooking eggs it is better, instead of boiling them, 

 to bring them as near the boiling point as you can, and then take 

 them off and keep them in the water a little longer. This makes 



