234 Chronicles of Science. [ April, 
acid, piperine, and narcotine. Next followed a list of substances 
which yielded about half of their nitrogen under the same circum- 
stances, among which we have morphia, codeia, papaverine, sulphate 
of quinine, and nicotine. Kreatine is an example of a substance 
which gives up one-third of its nitrogen as ammonia, while theine 
only yields one-fourth. Gelatine, casein, and dry albumen give up 
smaller, and apparently uncertain proportions; while picric acid and 
true nitro-compounds give up none. 
Mr. E. T. Chapman then read a note ‘‘ On the Decomposition 
of Nitrates by Sulphurous Acid; and another “On the Detection 
and Estimation of Nitrates in Potable Waters.” The estimation 
the author makes by converting the nitric acid into ammonia, by 
the action of aluminium and an alkali. The limits of error by the 
process he believes to be within five per cent. 
Mr. Perkin, F.R.S., afterwards read a paper “On the Hydride 
of Aceto-salicyl,” which was followed by two by Dr. Stenhouse, 
F.R.S., “On Chloranil,” and “On the Action of Nitric Acid on 
Picramic Acid.” Lastly, Mr. Chapman gave a short account of 
the “‘ Action of Zine Ethyl on Nitrous and Nitric Ethers,’ which 
is, it seems, sometimes attended with very violent explosions. 
The Secretary also read papers by Mr. Hunter, “On the Absorp- 
tion of Vapours by Cocoa-nut Charcoal,” and by Mr. F. A. Claudet 
“On the Crystalline Form of Arsenious Acid.” The author had 
obtained from the Pyrites Mine of San Domingos, Portugal, a 
quantity of fine crystals, similar in form to those first described by 
Wohler, as obtained by sublimation under peculiar circumstances. 
The crystals belong apparently to the same system as those of 
gypsum. This form cannot be reproduced by either solution or 
sublimation, in either case only the ordinary octohedral crystals 
being obtained. There are reasons for believing that active spon- 
taneous combustion is going on in a part of the mine mentioned, 
and the arsenious acid was probably sublimed in an atmosphere of 
sulphurous acid. 
6. ENGINEERING—CIVIL AND MECHANICAL. 
Waist the fear engendered by the late collapse of several rail- 
way and other companies still exercises its influence on capitalists, 
causing the suspension or abeyance of numerous promising under- 
takings in Civil Engineering, the combinations of mechanics, under 
the influence of Trade Societies, is rapidly having the effect, not 
only of disturbing the relations between employers and employed, 
but of diverting trade from its former centres, and in too many 
instances of driving it out of the country. Of this latter result, 
numerous examples might be instanced; but perhaps the most 
