380 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



acid gas pumped in under a pressure of 150 lbs. to the square 

 inch. The mixture can be kneaded and put into the oven with- 

 out delay. The bread is good in texture and quality, and will 

 keep sweet longer than bread made in the ordinary way. 



Mr. Dibben considered the effect of the mode of raising to be 

 so different from raising with yeast, that persons with weak 

 stomachs would object to it. Its novelty would be its chief 

 attraction. 



Mr. Seely considered the practical result in raising the bread 

 to be substantially the same as in raising it with yeast. It was 

 a question de gusiibus more than of anything else. Persons with 

 weak stomachs might be so influenced by their prejudices as to 

 find the bread difficult to digest. The experiment has been tried 

 of using atmospheric air instead of carbonic acid gas, but the 

 bread came out of a dark color, a circumstance which chemists 

 have been puzzled to account for. 



The Chairman stated that he had invited the proprietor of this 

 new machinery to come to the Association and bring a sample of 

 the bread, and that the subject would then be resumed. 



Mr. Johnson said that Mr. Garvey had suggested mixing the 

 flour with water merely, and then raising it by placing it in a 

 vacuum. Mr. J. had tried the experiment successfully. When the 

 dough is thus raised, and the air is let in upon it, it falls some- 

 what, but still is very light. 



ICE AND ITS FORMATION. 



The Association resumed the consideration of the question of 

 •' Ice, and Methods of Refrigeration." 



The Chairman requested Mr. Seeley to state the variety of 

 temperatures of the formation and melting of ice. 



Mr. Scely. — I believe it is settled that ice will melt uniformly 

 at the same temperature, 32 deg., but the freezing point, while 

 never higher than 32 deg., may, under certain circumstances, be 

 15 deg. below. Water, when peculiarly still, may be liquid at 

 the temperature of 17 deg. But if the water be then moved in 

 the least, by a breath of air, or the dropping in of a grain of 

 sand, it will instantly become solid. Water which is impure will 

 have a different freezing point. Adding alcohol, or certain salts, 

 to water, will reduce the temperature at which it freezes, very 

 much. 



Dr. Vanderweyde had witnessed the sudden freezing of water^ 

 which had remained liquid at 23 deg., by jarring the floor. The 



