Chemical Science, 409 



According to these results, which I have not had time to multiply, 

 Mr. Clarke's opinion of the cause requires to be modified. They 

 are sufficient, however, to make us conclude that very remarkable 

 differences exist between most phosphates before and after calci- 

 nation, or between those made with calcined or uncalcined acid. 

 It is to be remarked, that the modification of phosphoric acid by 

 heat is much more permanent when it is combined with a base than 

 when in aqueous solution. I hope to give other details on this sub- 

 ject at a future period. — Annates de Chimie, xli. 331. 



4. Production of Sulphuric Acid from the Vapours of the Aix 

 Waters. — The mineral hot waters of Aix, in Savoy, are two in num- 

 ber, and are distinguished, one as the aluminous, the other as the 

 sulphuretted. It has frequently been stated that the vapours of the 

 former contained free sulphuric acid. That they produce sulphuric 

 acid is proved by the following observations of M. Francoeur :— 

 i. All the grottos, closed chambers, corridors, &c. where the vapours 

 penetrate, have their walls corroded and covered with acid crystals 

 of sulphate of lime. ii. All iron utensils, &c. are not only cor- 

 roded, but often found incrusted with sulphates of iron and lime, 

 iii. Tubes of cloth, through which the vapours are passed, are quickly 

 rotted, and the rags are found impregnated with sulphuric acid. 



No free sulphuric acid exists in the water itself; and from the 

 circumstances it follows, that the mixture arising as vapour, and 

 containing hydrogen, azote, sulphur, and carbonic acid, has the 

 power of producing sulphuric acid by means of the atmosphere and 

 in contact with the walls and metal. — Ann. des Mi?ies t v. 285. 



5. Carburet of Sulphur decomposed by Voltaism. — M. Becquerel 

 has described an experiment on the decomposition of carburet of 

 sulphur by low voltaic powers. Liquid carburet of sulphur was 

 put into a tube (glass), and above it a solution of nitrate of copper: 

 then a plate of copper was plunged into and left in both solutions. 

 This formed a feeble voltaic pile, and chemical decomposition took 

 place. Both the carburet and the nitrate were decomposed, much 

 crystallized protoxide of copper was formed on the copper plate, and 

 carbon was deposited on the sides of the tube, in very thin plates, 

 with a metallic lustre. No formation of diamond. — Revue Encyc. 

 xliii. 508. 



6. Composition of the Atmosphere at Kazan. — The uniformity of 

 the composition of the atmosphere taken from different places and 

 heights upon the earth's surface is well known; but M. Kupffer 

 still thought it advisable, when he had the opportunity, to analyse a 

 portion of air collected at Kazan ; a place surrounded on the one 

 side by a poorly cultivated country, and on the other by the immense 

 steppes and forests of Siberia, where vegetation is dormant for the 

 greater part of the year. He used Volta's eudiometer, and still 



