NIEPCE'S PROCESS n.
A process, now no longer used, invented by J. N. Niepce, a French chemist, in 1829. It depends upon the action of light in rendering a thin layer of bitumen, with which the plate is coated, insoluble.
NITROHYDROCHLORIC a.
Of, pertaining to, or containing, nitric and hydrochloric acids. Nitrohydrochloric acid, a mixture of nitric and hydrochloric acids, usually in the proportion of one part of the former to three of the latter, and remarkable for its solvent action on gold and platinum; -- called also nitromuriatic acid, and aqua regia.…