170 ANNXTAX OF SCIENTIFIC DISCOVEKY. 



FREEZING MIXTURE. 



When citric acid and crystallized carbonate of soda in powder 

 are stirred together, the mass gets into a pasty state, and in a 

 short time becomes quite liquid. If ecjuivak'nt proportions of the 

 substances are used, the tem})crature lulls from GU° F. to 80° F. 

 The mixture, Ijor a time, is full of air-bubbles, but soon becomes 

 quite a clear, dense, syrupy liquid. The lluid obtained by mix- 

 ing the powders becomes solid in a day or two, standing in a 

 corked jar. The solid mass has the ai)pearance of set i)laster 

 ot" Paris. The addition ot" a very little water appears to prevent 

 this settling into a solid mass; but the chalky-looking citrate lies 

 a long time in cold water without being dissolved. 



NEW METHOD OF MAKING ICE. 



A few days ago a number of gentlemen, by special invitation, 

 witnessed the ojDcrations of a new invention which bids fair to be 

 one of great practical value. It is a process of making ice and 

 refrigerating by machinery, in a short space of time, at a com- 

 paratively small cost, and to an almost unlimited extent. The 

 working of this machinery was exhibited on board the steamship 

 " "William Tabor," lying in the East River, at the foot of Nine- 

 teenth Street, and its utility satisfactorily shown to the spectators. 

 This novel invention does two things: it makes ice with the 

 thermometer at 90 degrees in the shade, and preserves meats and 

 fruits for transportation. It accomplishes its purpose upon the 

 chemical principle that if all the heat is extracted out of any 

 object, it becomes intensely cold. The ice is made in this way : 

 A small steam engine, by means of two ]Miraps, subjects carbonic- 

 acid gas to a pressure sullieient to liquidize it. In a liquid state 

 this o-ixs has lost its heat, but recovers it ajjain when converted 

 into gas. Accordingly, a simple apparatus is contrived, by which 

 the aeitl in a liquid state is made to surround small tubes filled 

 with water. The acid then returns to its gaseous condition, and 

 in doing so takes with it all the caloric out of the water leaving 

 it solid ice. There is no limit to the number of these tubes or 

 apartments of water, and a laige quantity of ice can be formed 

 at a time. Yesterday about 20 tubes were filled and frozen to an 

 arctic rigidity. 



Upon the same principle air can be rendered cold and dry by 

 being passed through these tubes while carbonic acid is regain- 

 ing its heat, and then can be pumped into an air-tight chamber. 

 In tills chamber, thus filled with dry, frozen air, any meat, fruit, 

 or perishable article can be placed and preserved. 



THE BATHOMETER. 



This instrument admits of a combination in one sounding of 

 three or more distinct methods of ascertaining and measuring these 



