W. Gibbs on the Hexatomic compounds of Cobalt. 191 
erystals, the form and appearance of which are highly character- 
istic. These crystals gave no reactions with salts of luteo- 
cobalt, purpureocobalt and roseocobalt, and none with potassic 
chromate and dichromate, ammonic oxalate or argentic nitrate. 
The absence of the first mentioned reactions shows that they 
do not contain Co(NH,),(NO.)s or Co,{NO.)2, while the fact 
that they give no reactions with alkaline chromates and oxalates 
shows that they do not contain any known cobaltamin. Of 
ese crystals 
0°1554 gr. gave 0:0974 gr. SO,Co=23°86 per cent cobalt. 
0°3081 gr. gave 0°0635 gr. NH, =20°61 per cent ammonia. 
The formula Co,(NH;)(NO.), requires 
These analyses are sufficient to identify the salt in question 
with one which Erdmann has described in the paper referred to, 
as formed by the action of ammonia and potassic nitrite upon 
cobaltic chloride, unfortunately with but very scanty details. 
Co 
A 
ios 
t 
Z 
2 
7 * 
and consider it to be the nitrous representative of the hexamin 
H,). Ihave not succeeded in obtaining from it other 
members of the same series; but it is, to say the least, robable 
that the dichrocobalt-chloride of Fr. Rose,* Co,(N a)gClg) + 
20H,, represents the corresponding chloride. Kiinzel + has 
described a sulphite to which he attributes the formula 
Co,(NH,),(80s)s+OH:; 
‘but according to Geuthert this formula must be doubled, the 
— belonging to the dodekamin or luteocobalt series, with the 
ormula 
Co,(NH;)12 (SO;).+C02(803)¢ +20H,. 
Erdmann’s hexamin salt is of special interest because, as I 
shall show, it forms the first term in a remarkable series of 
metameric bodies; its formation under the circumstances may 
with great probability be expressed by the equation : 
20001, +10NH, .NO,-+30=Coa(NH3)o(NOa)et 4NEACT 
wt 
* Untersuchungen iiber ammoniakalische Kobalt-Verbindungen. Heidelberg, 
1871, 
+ Journal fir prakt. Chemie, 72, p. 209. $ Ann. de Pharmacie, 128, p. 127. 
