76 InteUiycnce and Miscellaneous Articles. 



breeze ; temperature, 24° C. ; north' latitude, 21° 9' ; west longitude, 

 42° 25'. 



December 4th, 1847, 3 a.m.: weather fine; wind north-west; 

 strong breeze ; temperature, 13" C. ; north latitude, 47° ; west lon- 

 gitude, 13°. 



Composition of the air in volume's. 



Oxysen. Nitrojjcn. Car. acid. 



December 18, f/ffy 21-d5^973 78-8.s6;J7 0-0005390 



December 4, ni(//it 20-96084 79006(iO 0-0003336 



The difference, it will be observed, is very appreciable; and as 

 the analj'ses were ))erformed with M. Regnault's eudiometer, the 

 author is of opinion that he can rely upon them to j^^thofthe 

 volume. 



The existence of the larger quantity of oxygen in the air taken 

 during the day, may perhaps be explained on the supposition that the 

 sun, by heating the surface of the sea, occasions a disengagement of 

 the air dissolved in the water, which air is richer in oxygen than that 

 of the atmosphere. It may be conceived that from this cause the 

 stratum of air in contact with the sea is affected in its composition. 

 — Comptes Rendus, Novembre 18, 1S50. 



ON THE CHEMICAL EQUIVALENT OF IRON. 

 BY M. E. MAUMENE. 



Many analysts have lately published the results -which they have 

 obtained with respect to this equivalent, the greatest variation being 

 from 339-23 to 350. The author had occasion to occupy himself 

 with this subject in 1846, being commissioned to analyse the wires 

 offered for the electric telegraph of the railway Du Nord, and having 

 found that the iron was perfectly pure, he made some experiments 

 to determine its equivalent. 



The metal being dissolved in weak aqua regia, the oxide was pre- 

 cipitated by ammonia, collected on a filter, very carefully washed 

 with hot water, dried in a stove at 110° centigrade, and then cal- 

 cined in a platina crucible. This method gives very good results 

 when all the hydrochlorate of ammonia has been removed by 

 washing. 



The numbers obtained were the following : — 



Mean 35001 



Comptes Rendus, Octobre 17, 1850. 



