374 M.C. Lea on Ammonia, Mercury, and Nitric Acid. 
essential to success in the construction of ocean telegraphs—perfect insu- 
lation, external protection, and appropriate apparatus for laying the cable 
safely on its ocean bed. That we are far from having succeeded in ful- 
filling these conditions is evident from the fact that out of 12,000 miles 
of submarine cable which have been laid since 1851, only 3,000 miles 
are in actual working order; so that three-fourths may be considered as 
a failure and loss to the country. The insulators hitherto employed are 
subject to deterioration from mechanical violence, from chemical decom- 
of merchants and manufacturers. This application of electric currents 
cannot be too hig 
tively small expense. To show to what an extent this improvement has 
been carri i 
Art. XLI—Note on a Compound of Ammonia, Mercury and 
Nitric Acid; by M. Carzy Lx, Philadelphia. 
Iw the course of an extended examination upon the reactions 
of the ethyl bases, I noticed that both etbylamine and diethyl 
amine gave with acid solution of mercuric nitrate a white pre 
cipitate which is permanent although the solution contains 4 
arge excess of acid. This compound did not appear worthy oi 
a special examination as it is no doubt analogous to that forme 
y ammonia under similar circumstances. But with respect 10 
the constitution of this latter I propose to offer a few remarks. 
The formula adopted for this compound by L. Gmelin, appat 
ently on the authority of Kane, ©. G. Mitscherlich and Pagen® 
techer, whose analyses are quoted, is 
NH,-+2Hg0, NO,. 
This view of the constitution is liable to two objections; first 
that it supposes the existence of the bibasic nitrate of mercury 
