438 Scientific Intelligence. 
ments. Dumas, in his well known memoir on the supe of the 
elements, asserted that he had determined the equivalent of manganese 
by reducing an artificial peroxyd to protoxyd by means of a current of 
hydrogen, and that he had found the number 26, as he expresses it, d’une 
maniere absolue. In a later communication, however, he gives the num- 
ber 27'5 as the true equivalent of manganese, the same being determined 
by the method of Berzelius. Schneider objects to the methods of Berze- 
lius and of von Hauer, believing that both are subject to constant sources 
of error. He has therefore determined the equivalent anew by the method 
already employed by him with cobalt and nickel, viz., by the analysis | 
pure neutral oxalate of manganese, the ratio between the carbon an 
manganese being sufficient for the purpose. In this manner four ae 
to ye Se 29, acne dectonale { in the second and. third places. 
In a third paper on equivalents and on the determination of equiva- 
lents in general, Schneider has given a very severe, but at the same time, 
os at criticism of Dumas’ two memoirs on the. sicmie weights of the 
elemen 
¢ lai 
alkaline salt. The arudible 3 is then heated till the mass fuses. When on 
removing the cover for an instant, a zinc flame is observed, accompanied 
by a peculiar souud, the heat is dinnittished by closing the draught, and 
mass kept about ten minutes in fusion. The crucible is then to be 
seeed. from the fire, gently struck to collect the metal, and allowed 
to cool. On breaking the cricible, a well fused Ms ote: of zine is found 
under a green slax. After being well cleaned in water, it is to be place 
in dilute nitric acid, which is to be frequently reneved till all the zine is 
dissolved. e chromium remains as a crystalline pore which is again 
sharp thombohedrons of great ee = almost tin-white aie tet ope 
cific gravity is 6-81 at 25° C.; it magne nati ic. Heated in the air, it 
oxydizes, becoming yellow and “pee "Tike steel, and gradually 
covered with a thin layer of green oxyd. When heated in chlorine, it 
& 
; 
j 
