Siilphtii-tc Acid.—Cciigelatlon of Mercury. — Ebjic Fluids. 4^j 



The memoir of Fourcroy and Vauquelin on the fulphureous acid, confids in an exami- 

 nation or hiftory of its adion on every known fubftance. They, in the fir.1 place, examined 



this adlion 



f calori 

 upon i 



\ oxyge 



next on the acids 



afterwards on the combiifllbles 



one 



ygene gas, 

 r fulphuric rpotafa 



J nitric **''''^ ^^^ alk-ili3< foda 

 [ muriatic l immoniac, 



hydrogen 



phofphorus I 



phofphoratedhydrogcngas with the earths] , 

 fulphurated hydrogen gas I " 



carbon Lmagnef.a. 



paUimine 

 ime 



In every cafe wherein the fulphureous acid formed a fait by combination, thefe chemifls 

 have dcfcribed the form of its cryftals, its fufibility, the affmities and proportion of conftl- 

 tuent parts. 



This memoir prefents a complete table of the binary combinations of the fulphureous 

 acid, and renders it very defirable that the authors fhould continue, for the advancement of 

 fcience, to publifli fimilar accounts of a great number of fubftances, on which our notions 

 are yet very incomplete. 



The three memoirs of general phyfics : i. Of the congelation of mercury, by Haflen- 

 fratz, Bonjour, and Welte. 2. The laws of dilatation in elaflic fluids, by Prony, 3. The 

 influence of fnow atid rain on vegetation, by HaflTenfratz. 



It has long been known, that m.ercury was rendered folid at Peterfburg by cold 24 degiees 

 of Reaumur below zero, and that in this ftate it becomes malleable. The experiment was 

 repeated at London by Cavendifti, by producing the fame degree of artificial cold ; but thi? 

 refult had never been obtained in France. 



The memoir of Haflcnfratz on the congelation of mercury contains only a repetition of 

 this experiment, in vi'hich the proportion of caloric, abforbed during the congelation of the 

 metal, is determined, which had not before been done by any pliilofopher. This experi- 

 ment has afTordcd a very curious refult. In water the caloric, abforbed during the tranfition 

 from the folid to the fluid ftate, is fufTicient to have raifed its temperature 60 degrees Reau- 

 mur ; and in mercury the quantity to produce the fame e{Fe6t would have been fuflrcirnt 

 to raife the temperature 64 degrees. 



In order to afccrtain the principle and the laws to which a great number of phenomena 

 are referab!?, it is nccclTirry to make a feries of reiterated experiments on the fame facts. 

 This is attended with two kinds of difficulties, namely, the time they require, and the im- 

 pcrfcftion of the inftrument. 



Neverthelefs, wlien the exiftence of a law in the progrefs of any phenomenon is afcer- 

 i.aincd, it is always fioffible, from a fmall number of experiments, to difcover by analyfis an 

 equation which may cxprefs the law. 'J'his is the object of tlie memoir which Prony has 

 printed in the fccond Cahier of the Journal of the Polytcclinic School. It is divided into 

 two parts. In the firfl he invefligates a method of interpolation applicnble to the phenomena 

 which depend on eladic fluids ; in the fccond he applies this method to a'fccrtiin the law 



of 



