On the Produ^kn of artificial Cold, 32 j 



l^rom the preceding account it is apparent, that Pr. Lowitz has difcovered a fingle fri- 

 ;gorific mixture, by which quickfilver may be frozen whenever the temperature of the ma- 

 terials at mixing is no colder than ■■(- 32" ; whereas, the nitrous acid with fnow, which has 

 tithertobeen confidered as the moft powerful of frigorific mixtures, requires a temperjiture 

 ■of + 7°, to produce the fame efFeft. 



At the fame time, however, it (hould be obferved, that an experiment with this fait, 

 prepared as above, can be made only during a freezing atmofphere ; the fait itfelf thus pre- 

 pared, becoming, as may be inferred from the above, and as I have myfelf experienced, 

 unfit for ufe by a warmer temperature. 



Reflecting upon my former experiments, I determined to try the effedl of this fait, re- 

 duced to fuch a ftrength, by evaporation, as to endure being kept, in a folid ftate, 

 throughout the year. For this purpofe, I found it neceflary that the liquor, prepared as 

 before, fliould be evaporated to the confidence of a thickifli fyrup, before it is fet by to 

 cryftallize ; when the produce will be a femi-tranfparent, uniform, cryftalline mafs, which 

 affords, on pulverizing, a white pearl-coloured powder, which fhould be preferved for ufc 

 in a bottle clofed with a ground ftopper. 



Some of the powder above mentioned, (which had been preyloufly fubje£ted to a tem- 

 perature of + 70°, without melting,) I mixed with fnow, each at the temperature of + 

 32°; when the thermometer, to my perfe£l: fatisfa£lion, funk to — 40°; and, at another 

 time, when the air was + 20°, I froze quickfilver perfedly folid, by a mixture of the 

 fame materials. 



It appeared reafonable to expeft that the power of this fait for producing cold, might 

 be affifted by the combination with, or addition of, other falts, as has been found to be the 

 cafe in other indances, to a confiderable degree ; and, conceiving from my former expe- 

 riments, that the muriate of foda and nitrate of ammonia promifed the greateft fuccefs ia 

 this way, thefe alone producing with fnow a cold of — 25 °, I was naturally led to com- 

 Wne thefe with the muriate of lime; but I obtained no advantage by this, or by any other 

 nieans, worth noticing. *. 

 , " In the courfe of lalt winter, and the fummer preceding, I repeated my former experi- 

 ments with more accuracy ; and likewife made fome additional ones, on the power of mu- 

 riate of lime for producing cold with ice, the refult of which I (hall here briefly ftate. 

 c In order to reduce the experiments made with the muriate of lime to a greater certainty, 

 I carefully obtained the refpedive fpecific gravities to which this fait fliould be reduced by 



* M. Yan Mons tried the effe6l of the cauftic foda (which alone produces a cold of — 15° with fnow) 

 combined with the muriate of lime, and found the eft'eft incrcafed very confidevably. By this means, he 

 fays, ." In my new experiments on the effefts of artificial cold, I have carried it to — 53°, old divificn" j 

 (viz. 87° of Fahrenheit.) He does not mention the temperature at which the materials were mixed; to 

 produce this effe£t. — M. Van Mons effeils a chemical union of thefe two falts thus : he flakes <)Tiicklime 

 with a folution of muriate of foda; this mixture, when become cold, he filters, and aftei^wards evaporates, 

 until when cold it will become folid. Annates de Cbimie, torn. XXIX, 



"VoL.V. — September 1801. Gg evaporation, 



