344 BORATES. 



Sp. 2. Sulphate of Magnesia. — This salt well known by the 

 name of Epsom Sail, sometimes forms an efflorescence, and is 

 contained in various mineral waters, as in those of Epsom in Surry, 

 whence it has been extracted, but at present it is principally 

 obtained from the liquor remaining after sea- water has been boiled 

 down for common salt. It is used as a cathartic in a dose of from 

 ■=i. to ~ii. dissolved in any proper vehicle. 



The remarks made upon the other native sulphurets, as those of 

 iron, copper, and zinc, in a former part of this work, render any 

 further observations superfluous. 



Genus V.— NITRATES. 



Sp. 1. Nitre, or Nitrate of Potash. — This salt occurs form- 

 ing incrustations, and in groups of capillary crystals on the surface 

 of the soil and on rocks. It is found in great abundance in various 

 parts of Europe, Asia, and Africa. The nitre used for the manu- 

 facture of gunpowder in the United States of America, is said to be 

 obtained from an earth collected in the limestone caves of Kentucky. 

 It is brought to this country in an impure state from India. It is 

 purified by repeated solution and crystalization. As a medicine, 

 this neutral salt is sometimes prescribed as a diuretic, but more 

 commonly as a refrigerant and sedative in all inflammatory com- 

 plaints, excepting those of the urinary organs, in active hsemor- 

 rhagies, and in herpetic eruptions. It is given in the dose of from 

 5 to 20 grains, repeated every four or five hours. In very large 

 doses, as from 5ss. to si. for instance, it occasions violent nausea 

 and pain in the stomach, vomiting, spasms, and bloody-stools, and 

 sometimes proves fatal. In such cases, mucilaginous drinks, general 

 and local bleeding, and opiates, are the most effective remedies. 



Genus VI.— BORATES. 



Sp. 1. Borate of Soda, or Borax. — Sodas Boras, Ph. Sal 

 Sedativus, Etmlerg —This salt is chiefly brought from Thibet and 



