248 Scientific Intelligence. 
difficulty a second but smaller disc of glass is placed on the same axis, 
coated with tin foil in the same manner and provided with a similar in- 
ductor and similar conductors. This second inductor is connected with 
one pole or conductor of the upper and larger plate. Of the two similar 
conductors belonging to the lower plate, one is connected with the earth 
while the other is connected with the inductor of the upper plate, In 
this manner, as the discs rotate, the earth furnishes a constant supply of 
ores and the action of the machine is remarkably powerful. Holtz’s 
achine depends upon —— paar ee but could hardly be made in- 
telligible without figures. eral o m have 7 sascha in this 
A simpler form of spain 8 of the sam as since been 
described by Bertzch, All these instruments < r to be aris much 
more powerful than plate electrical machines of the same size, and they 
have the advantage of working with but a small application of foree— 
Pogg. Ann,, exxv, 469; also Holtz i in Pegg. Ann., exxvii, 320; cee 
in = 1866. 
Bs 
E 
Ni pe prea hc by Lan sia Rammelsberg. ee a solu- 
tion of this salt-is ws with one of chlorid of calcium, or when nitrite 
of potash is added t solution oo both nickel and calcium, a 
yellow crystalline prsipitate is formed ae is — slightly soluble in 
cold but much more solu n hot water. ution is green, but the 
salt is always more or less peor osed, When ihe salt is formed slowly 
it crystallizes in well-defined regular octahedrons. Its constitution 1s 
represented by the formula 
NiO 
CaO, NO,+-NiO.NO,+KO, NO, or CaO } 3NO,. 
KO 
The corresponding barium salt has been deseribed by Lang. It is also 
mg slightly soluble in x on and crystallizes in microscopic cubes with 
ahedral faces. e strontium salt forms reddish-yellow crusts con- 
| shite of microscopic sabia Cobalt forms eo analogous com- 
pounds. The triple nitrite of cobalt, potash and lime, forms a black- 
green crystalline precipitate. The salts of cobalt with barium and stron- 
tium, have a still more beautiful green color, bit like the calcium salt 
are decom y washing. ‘The ammonia nitrite of nickel, which 
Erdmann terms nitrite of diamin- nickel, forms pace vi brilliant 
crystals having the formula 2NH,.NiO, NO easily dee mposed. 
mixture of two: different salts, one of which is enna Yo in an acid and 
other in a neutral solution. The salt formed in a neutral solution has 
the formula nein 3 ; 8NO,-+HO. It is a yellow crystalline powder 
composed of perth cubes. The author has satisfied himself that 
no absorption of oxygen takes place during the formation of this salt, 
