NITRATE OF SODA. 473 



times before the nitre is sufficiently pure for the manufacture of gun- 

 powder. 



9. USES. Nitre* is an important substance. It is nearly indis- 

 pensable in the manufacture of the nitric and sulphuric acids. In 

 medicine it is given as .a diuretic, and cooling remedy ; it is a pow- 

 erful antiseptic, and is much used in the salting of beef, to the fibre 

 of which it gives a fine red color, and great firmness. f 



It is given only in inflammatory states of the body, 5 to 20 grains 

 at a time, and not exceeding 1 or lj drachms in a day ; it di- 

 minishes heat and vascular action, and is cathartic. 



In a dose of an ounce, it is a violent poison, and has often been 

 sold and given by mistake, for sulphate of soda. It can always be 

 distinguished by throwing it on burning coals, when if genuine, it 

 will deflagrate ; and by the emission of fumes of nitric acid, when 

 sulphuric acid is added to it. 



In Chemistry, it affords oxygen gas ; it imparts oxygen to many 

 substances which- cannot be made to combine with it in any other 

 way, as to metallic titanium, which resists even nitro-muriatic acid. 

 It is employed in metallurgic operations, in the assaying of ores, and 

 it is used to determine, by deflagration, the proportion of carbonace- 

 ous or other combustible matter contained in a soil, in coal, &c. It 

 has^changed the whole art of war ; and in naval conflicts, gunpowder 

 is, and must remain, the principal means of annoyance. 



NITRATE OF SODA. 



1 . NAME AND PREPARATION. Formerly called cubic nitre, from the 

 obtuse rhomboidal form of its crystals. It is prepared by saturating 

 soda, or its carbonate, with nitric acid; it is not known in the shops. 



2. PROPERTIES. 



(a.) Taste more bitter than that of nitre, but its general proper- 

 ties very similar. 



J^.) Rather more soluble, requiring only 3 parts of water at 60, 

 less than its own weight at 212. 



(c.) Effected by heat, acids and combustibles, in the same manner 

 as nitre, but is less fusible. 



(d.) Slightly deliquescent, and therefore unfit for making gunpow- 

 der. 



3. COMPOSITION. According to Dalton, 57.6 and 42.4 base, but 

 Dr. Henry remarks that these numbers do not agree with equivalent 

 proportions. On the authority of Wenzel, quoted by Brande,{ it is 



* For the sake of brevity, I have generally, in this article, used the word nitre in- 

 stead of nitrate of potassa. 



t Muscular fibre after being thoroughly impregnated with salt, especially with the 

 addition of nitre and dried, becomes nearly imputrescible. In the Leverian museum, 

 in London, I saw beef in 1805^ a remnant of the provisions with which Lord Anson 

 performed his circumnavigation, from 1739 to 1744. 



\ Tables of definite proportions. 



60 



