422 NITRO-GLYCERINE 



acid, by the agency of nitre. It is formed by mingling four volumes of binoxide of 

 nitrogen with one volume of oxygen ; and appears as a dark -orange vapour, which is 

 condensable into a liquid at a temperature of 4 below zero, Fahr. When distilled, 

 this liquid leaves a dark yellow fluid. The pure hyponitrous acid consists of 37'12 

 nitrogen and 62'88 oxygen ; or of two volumes of the first, and three of the second. 

 Water converts it into nitric acid and binoxide of nitrogen ; the latter of which 

 escapes with effervescence. This acid oxidises most combustible bodies with peculiar 

 energy ; and though its vapour does not operate upon dry sulphurous acid, yet, 

 through tho agency of steam, it converts it into sulphuric acid, itself being simul- 

 taneously transformed into binoxide of nitrogen ; ready to become hyponitrous acid 

 again, and to perform a circulating series of important metamorphoses. See SULPHU- 

 BIC A<m 



NITROGEN, PROTOXIDE: OP, or Nitrous Oxide (Protoxide d'asote, Fr.; 

 Stickstoffoxydul, Ger.), NO (l^O), is a gas which displays remarkable powers on tho 

 system when inhaled, causing in many persons unrestrainable feelings of exhilaration, 

 whence it has been called the laughing or intoxicating gas ; but the effects often vary. 

 When pure this gas does not seem to be injurious; but the bad effects which 

 sometimes follow its use are most probably due to the use of the gas when not quite 

 pure. It is now used by dentists and surgeons as an anaesthetic. 



Jt was first discovered by Dr. Priestley in 1776, and was afterwards studied by Sir 

 H. Davy, who called it nitrous oxide; it was Davy also who first observed its stimu- 

 lating effects when taken into the lungs. 



It is prepared by heating solid nitrate of ammonia in a flask, provided with a bent 

 tube to carry away the gas ; care must be taken in applying the heat, to avoid the 

 tumultuous disengagement of the gas ; the nitrate melts and enters into gentle ebulli- 

 tion, and the gas is steadily evolved. If too much heat be applied, the flask becomes 

 filled with white fumes, which have an irritating odour, and the gas which comes over 

 is little else than nitrogen. Protoxide of nitrogen should always be collected over 

 warm water, as cold water dissolves nearly its own volume of this gas. The following 

 equation expresses the decomposition of the nitrate of ammonia : 



NH 4 N0 6 m 2ND + 4HO (NH 4 NO 3 = W 2 O + 2H 2 O) 



the only products being water and protoxide of nitrogen. Protoxide of nitrogen, at 

 ordinary temperatures, is a colourless, transparent, and almost inodorous gas, of dis- 

 tinctly sweet taste. Its specific gravity is T525; 100 cubic inches weigh 47'29 grains; 

 it is therefore much heavier than atmospheric air. It supports the combustion of a 

 taper or a piece of phosphorus with almost as much energy as pure oxygen ; it is 

 easily distinguished, however, from that gas by its solubility in cold water, and by not 

 forming red fumes when mixed with binoxide of nitrogen. It has been liquefied, 

 although with difficulty ; it requiring at 45 Fahr. a pressure of fifty atmospheres ; the 

 liquid when exposed under the bell-glass of an air-pump is rapidly converted into a 

 snow-like solid. 



When mixed with an equal volume of hydrogen, and fired by the electric spark in 

 the eudiometer, it explodes with violence, and liberates its own measure of nitrogen ; 

 every two volumes of the gas contain therefore two volumes of nitrogen, and one 

 volume of oxygen condensed into two volumes. By weight it contains 14 parts 

 of nitrogen to 8 of oxygen. See LAUGHING GAS. 



NTTRO-GXiUCOSE. When we act on finely-powdered cane-sugar with nitro- 

 sulphuric acid, a pasty mass is first formed ; if this bo stirred fora few minutes, lumps 

 separate from the liquid. When these lumps are kneaded in water, until every trace 

 of acidity is removed, they acquire a white and silky lustre ; these are the above-named 

 substance. 



NTTRO-GIYCERINE. A compound produced by the action of strong nitric and 

 sulphuric acid on glycerine at a low temperature. The following modes of preparation 

 are from Watts's ' Dictionary of Chemistry' : 



1. A hundred grammes of syrupy glycerine of specific gravity 1'262 are gradually 

 added to 200 c.c. of nitric acid of specific gravity 1-52, immersed in a freezing mixture, 

 the liquid being continually stirred, the temperature allowed to fall to 10 Cent, 

 before each fresh addition, and never to rise above 0. A homogeneous mixture having 

 been thus obtained, 200 c. c. of strong sulphuric acid are gradually added, the mixture 

 being still kept below 0. The oily nitro-glycerine (200 grms.) which then floats on 

 the surface is separated by a tap-funnel from the acid liquid (which yields 20 grms. 

 more of nitro-glycerine on being diluted with water), and dissolved in the smallest 

 possible quantity of ether; the solution is repeatedly shaken with water till tho 

 water no longer reddens litmus ; the ether evaporated, and the remaining nitro- 

 glycerine heated over the water-bath until its weight remains constant. The product 





