NIT 



NIT 



Iy as nature has not laid up large maga- 

 zines of it, as she has of other salts. It is 

 now ascertained, that nothing 1 more is 

 necessary for the production of nitre than 

 a basis of lime, heat, and an open, but 

 not too free communication with dry at- 

 mospheric air. When these circum- 

 stances combine, the acid is first formed, 

 and afterwards the alkali. See XITHIC 

 acid. 



NITRE. See NITHATES. Nitre is 

 found abundantly on the surface of the 

 earth, in India, South America, South 

 Africa, and even in some parts of Spain. 

 In Germany and France it is obtained by 

 means of artificial nitre-beds. These 

 consist of the refuse of animal and vege- 

 table bodies, undergoing putrefaction, 

 mixed with calcareous and other earths. 

 It has been ascertained, that if oxygen 

 gas be presented to azote at the instant of 

 its disengagement, nitric acid is formed. 

 This seems to explain the origin of the 

 acid in these beds. The azote, disen- 

 gaged from these putrifying animal sub- 

 stances, combines with the oxygen of the 

 air. The potash is probably furnished, 

 partly at least, by the vegetables and the 

 soil. The nitre is extracted from these 

 beds, by lixiviating the earthy matters 

 with water. This water, when sufficient- 

 ly impregnated^" is evaporated, and a 

 brown-coloured salt obtained, known by 

 the name of crude nitre. It consists of 

 nitre, common salt, nitrate of lime, and 

 various other salts. The foreign salts are 

 either separated by repeated crystalliza- 

 tions, or by washing the salt repeatedly 

 with small quantities of water : for the 

 foreign salts being more soluble, are 

 taken up first. Nitre, when slowly eva- 

 porated, is obtained in six-sided prisms, 

 terminated by six-sided pyramids ; but 

 for most purposes, it is preferred in an 

 irregular mass, because in that state it 

 contains less water. The specific gravity 

 of nitre, as ascertained by Dr. Watson, is 

 1.9. Its taste is sharp, bitterish, and 

 cooling. It is very brittle. It is soluble 

 in seven times its weight of water, at the 

 temperature of 60; and in rather less 

 than its own weight of boiling water. 

 When exposed to' a strong heat it melts, 

 and congeals by cooling into an opaque 

 mass, which has been called mineral crys- 

 tal. Whenever it melts, it begins to dis- 

 engage oxygen ; and, by keeping it in a 

 red heat, about a third of its weight of 

 that gas may be obtained : towards the 

 end of the process azotic gas is disengag- 

 ed. If the he:it be continued long enough; 

 the suit is completely decomposed, and 

 pure potash remains behind. It deto- 



nates more violently with combustible bo- 

 dies than any of the other nitrates. When 

 mixed with one-third part of its weight of 

 charcoal, and thrown into a red-hot cru- 

 cible, or when charcoal is thrown into 

 red-hot nitre, detonation takes place, and 

 one of the most brilliant combustions that 

 can be exhibited. The residuum is car- 

 bonate of potash. A still more violent 

 detonation takes place, if phosphorus is 

 used instead of charcoal. Nitre oxydizes 

 all the metals at a red heat. The compo- 

 sition of nitre, according to Kirwan, is 



Acid 44 



Potash 51.8 



Water . 4.2 



100.0 



Nitre furnishes all the nitric acid in all 

 its states, employed either by chemists or 

 artists : it is obtained by decomposing it 

 by means of the sulphuric acid. When 

 burnt with tartar, it yields a pure carbon- 

 ate of potash. In the assaying of various 

 ores it is indispensable, and is equally ne- 

 cessary in the analysis of many vegetable 

 and animal substances. But one of the 

 most important compounds, formed by 

 means of nitre, is gunpowder, which has 

 completely changed the modern art of 

 war. The discoverer of this compound, 

 and the person who first thought of ap- 

 plying it to the purposes of war, are un- 

 known. It is certain, however, that it 

 was used in the fourteenth century. 

 From certain archives, quoted by Wieg- 

 leb, it appears that cannons were employ- 

 ed in Germany before the year 1372. No 

 traces of it can be found in any European 

 author, previous to the thirteenth centu- 

 ry ; but it seems to have been known to 

 the Chinese long before that period. 

 There is reason to believe, that cannons 

 were used in the battle of Cressy, which 

 was fought in 1346. They seem even to 

 have been used three years earlier at the 

 siege of Algesiras ; but before this time, 

 they must have been known in Germany, 

 as there is a piece of ordnance at Amberg, 

 on which is inscribed the year 1303. Ro- 

 ger Bucon, who died in 1292, knew the 

 properties of gunpowder ; but it does 

 not follow that he was acquainted with its 

 application to fire-arms. See GUXPOW- 

 DEII. When three parts of nitre, two 

 parts of potash, and one part of sulphur, 

 all previously well dried, are mixed toge- 

 ther in a warm mortar, the resulting com- 

 pound is known by the name of fulminat- 

 ing powder. If a little of this powder be 



