Chemistry and Physics. 



403 



c - c -(«+t 0 )p[dv + A -*y 



and hence for the second factor the expression 



dU - . fl+^o / t \ 



— + A.pz= -J_2-( c '-c)j>. 

 dv P 0 ' v o 

 By substituting these expressions in (2), we have 



(3) dQ = cdt + ^-^(c'-c)pdv, 

 Po- v o 



or if we signify the integration 



(4) Q= f cdt + a -+^-f(c'-c)p< 



_ dv, 



Po 



which is the sought equation. It is easy to see also that a deviation from 

 the laws of Mariotte and Gay Lussac can be taken into consideration in 

 this investigation as easily as in that of Hoppe. — Pogg. Ann. xcviii, 1*73, 

 May, 1856. 



3. On Ozone. — Andrews has communicated the results of a very 

 elaborate and extended investigation of this subject, which forms an im- 

 portant contribution to our knowledge. The author in the first place 

 repeated the experiments of Baumert, who arrived at the conclusion that 

 ozone is a peroxyd of hydrogen, having the formula HO 3. Andrews 

 found that no two experiments led to the same constitution for this per- 

 oxyd, and finally discovered that the discrepancy was owing to a small 

 quantity of carbonic acid which, without great care, is always mixed with 

 electrolytic ozone. In Baumert's experiments the increase of weight of 

 the apparatus was always greater than the weight of the ozone as deduced 

 from its chemical action. Andrews found, however, that when the car- 

 bonic acid was completely removed these two quantities exactly agreed, 

 so that it is proved that water is not a product of the decomposition of 

 ozone, and therefore that this contains no hydrogen. In like manner it 

 was shewn that no water is produced when ozone is decomposed by heat. 

 The ozone obtained by electrolysis by the action of the electric spark and 

 by the oxydation of phosphorus was found to be identical. Finally, it 

 was found that ozone contained no nitrogen. The author concludes from 

 his investigation that ozone is oxygen in an allotropic modification, and 

 not a compound body as supposed by Schonbein, Williamson, and Bau- 

 mert. — Phil. Tr.for 1855, quoted in Pogg. Ann. xcviii, 435, June, 1856. 



4. Preparation of Aluminum. — Brunner has prepared aluminum 

 directly from the fluorid instead of employing cryolite. The fluorid is 

 prepared by dissolving alumina in fluohydric acid, or rather by condens- 

 ing the acid in the alumina. The fluorid is then reduced by sodium in a 

 hessian crucible, a layer of common salt being placed above the mixture. 

 The yield is not stated. — Pogg. Ann. xcviii, 488. 



5. On the conversion of carbonic oxyd into formic acid, and on the 

 preparation of formic from oxalic acid. — Bert-helot has found that when 

 carbonic oxyd is heated in contact with hydrate of potash, formate of 

 potash is produced, the reaction being represented by the equation 



2CO + KO, HO = C2HO3, KO. 



