Liquefaction and Solidification of Carbonic Add. 347 



M. Thilorier found also that the expansive force is altered by 

 heat so as to amount at 86° to 73 atmospheres, and at — 4° to 

 26 atmospheres. The density of the gas when resting over the 

 hquid at 86°, is stated at 130 times the density of that which is 

 compressed by the force of one atmosphere. Its pressure is there- 

 fore at 86° not much more than one half of that which its den- 

 sity would indicate. 



When liquid, the carbonic acid is, on the same authority, im- 

 miscible with water and the fat oils, but is readily united with 

 ether, alcohol, naphtha, oil of turpentine and carburet of sulphur. 

 Although potassium decomposes it, lead, iron, copper, and the 

 other easily oxidized metals, do not act on it.* 



The thermometric temperature observed in the jet by Thilorier, 

 appears to be erroneously stated ; for, as the solid is, at its forma- 

 tion, not below — 90°, and as the act of solidification of any vapor 

 or liquid keeps the temperature, for the time, at the highest point 

 compatible with the existence of the particular solid under ob- 

 servation, it follows that the jet of carbonic acid cannot fall 

 below its freezing point. Immediately after its production, the 

 carbonic snow begins to grow colder, and may be made to reach 

 — 109° in the air, — -136° under an exhausted receiver. When 

 moistened with ether, it can be depressed to — 146°. Professor 

 Hare's ether acts much more effectually than sulphuric ether.f 



At the immediately subsequent sitting of the Academy of Sci- 

 ences, Thilorier announced the important fact that he had solid- 

 ified carbonic acid. This he effected by suffering the liquid to 

 escape into a bottle, or box, where, by the sudden gasefaction of 

 a part, the remainder was frozen by the extreme cold thus pro- 

 duced. The solid is white, light, evaporable, and excessively 

 cold. Because, surrounded by an atmosphere of gas which is 

 constantly escaping from it, a fragment of it touched lightly by 

 the finger, glides rapidly as over a plane surface. 



Its evaporation is so complete as to leave no other trace of 

 moisture than that which is caused by the coldness and conse- 

 quent atmospheric humectation. 



* Among the most remarkable of the phenomena observed by Thilorier, was 

 the intense cold produced by the sudden liberation of the liquid and its conversion 

 into gas. A jet of it depressed the thermometer to — 130° F., and when sulphuric 

 ether had been previously mixed with the liquefied gas, the refrigerating effects 

 were more marked both on mercury and the sensations. 



t See Dr. Hare's account of his Ether, at page 328, in this number. — Eds. 



