Scientific NewSy Accounts of Books, Be, 379 



Thus It appears (experiment 2.) that it is at the moment when the iron has tlecompofed 

 almoft all the nitric acid, and it becomes neceflary alfo to decompofe the water, in order 

 to oxidate more metal ; that the muriatic acid, and the greateft part of the ammoniac, 

 is formed by the decompofitlon of the water. 



It is to the prefence of oxygen, azote, and hydrogen, that citizen Berthollet attributes 

 the formation of muriatic acid in artificial nitre beds, when the materials do not pre- 

 vioufly contain any muriate. 



Although muriatic acid, from the proportions of its conftituent principles, ought ftrongly 

 to refift decompofitlon, citizen Berthollet thinks that he has obferved that this decompo- 

 fition takes place under fome circumftances. 



He thinks that the refidue which is left by oxygen gas difengaged by heat, from oxigenated 

 muriate of pot-afli, is owing to the decompofition of a fmall portion of this acid. He 

 had, at firft, attributed this refidue to a foreign caufe ; but having remarked that it was 

 more abundant at the end than at the beginning of the operation, he conceived it could not 

 refult from fuch a caufe. , - 



Citizen Berthollet clofes his Memoir, by (hewing, from more accurate experiments, that 

 the black colour which muriate of filver aflumes from'light, heat, and even from a fimple 

 current of air, ought not to be attributed, as he himfelf had fuppofed, to a gafeous dif- 

 engagement of oxygen, but to the feparation of a part of the muriatic acid, without 

 decompofition. 



SCIENTIFIC NEWS, ACCOUNTS OF BOOKS, 8(c. 



Phihfophlcal TranfaEllons of the Royal Society of London, for the Tear 1800. Part the 

 Second, ^arto, 46 Pages, ivith Eleven Plates. London, fold by Elmfley. 



A HIS part contains. — 12. On double images, caufed by atmofpherlcal refradion. 

 By William Hyde, Wollafton, M. D. F. R. S. (fee our prefent, vol. p. 298.) 13. Invef- 

 tigation of the powers of the prifmatic colours to heat and illuminate obje£ls; with 

 remarks, that prove the different refrangibility of radiant heat. To which is added, an 

 enquiry into the method of viewing the fun advantageoufly, with telefcopes of large 

 apertures and high magnifying powers. By William Herfchel L. L. D. F. R. S. 14. Ex- 

 periments on the refrangibility of the invifible rays of the fun. By William Herfchel, L, L. D. 

 F. R. S. (abridgment of thefe two papers is given at p. 320) of our prefent volume. 

 15. Experiments on the folar, and on the terreftrial rays that occafion heat ; with a com- 

 parative view of the laws to which light and heat, or rather the rays which occafion them, 

 are fubjeQ, in order to determine whether they arc the fame, or different. By William 



3 C 2 Herfchel, 



