284 W. Gibbs on the Heaxatomic compounds of Cobalt. 
t one, fe) 
Pascal, Leibnitz, Babbage and Scheutz will acknowledge. 
Pascal speaks of his invention as “a work of some years. 
Leibnitz, at the height of his fame, devoted four years to this 
object, and failed; Babbage worked from 1822 to 1842 on his 
to 1854 bringing his machine to the partially successful condi- 
tion it is now in. The machine described above for the first 
time is the result of nearly four years of study and labor. 
Cambridge, Mass. July 15, 1874, 
Art. XXV.— Researches on the Hexatomic compounds of Cobalt; 
by Woxcorr Gripss, M.D. 
[Continued from page 200.] 
Bromo-nitrate of xanthocobalt,—One molecule of bromide of 
xanthocobalt was mixed with one of the nitrate of the same base, 
both salts being in solution in hot water, A dark, sherry-wine- 
colored salt separated, after some hours, in well defined crystals. 
In this salt 
0°8925 gr. gave 04190 gr. SO, Co=17'86 per cent cobalt. 
0°7116 gr. gave 0-1244 or. silver —12-94 per cent bromine. 
The formula Co,(NH,) , o(NO,),(NO,), Br, requires 17°77 per 
cent cobalt, and 24:09 per cent bromine. The salt was re- 
dissolved and allowed to crystallize a second time. In the salt 
thus obtained 
0°8538 gr. gave 0°3984 pr, S0,Co=17-76 per cent cobalt. 
0°8474 gr. gave 0°2672 gr. silver —23-69 per cent bromine. 
These results leave no doubt that a definite bromo-nitrate, 
analogous to the chloro-nitrate, is formed by direct union of 
the nitrate and bromide. The salt appears to be, however, 
. po: 
and then gave 23°04 per 
encement ol a separation 
