VOL. LXXXII.] PHILOSOPHICAL TRANSACTIONS. 151 



in a state of combination with the aerial and other acids. — Exper. II. Caustic 

 fixed alliali precipitated from the fresh water aerated magnesia. 



Exper. 12. On dropping muriated terra ponderosa into the fresh water, the 

 earth is precipitated ; which also happens, but in a less degree, if the water has 

 been boiled ; this proves it to contain vitriolated soda and magnesia, the other 

 selenite. To ascertain the quantity of vitriolic acid contained in these salts, as 

 much pure acetous acid was first added to 1 lb. of the water, as was required to 

 saturate the earth. Then a solution of terra ponderosa in nitrous acid was care- 

 fully dropped into the mixture, till no more precipitate was formed ; the thus re- 

 generated spar was carefully collected, edulcorated, and dried, when it weighed 

 6o grs. Now, if 100 grs. of ponderous spar contain 11 grs. of vitriolic acid, it 

 will follow, that J lb. of the Kilburn water contains about 13 grs. of this acid. 



Exper. 13. Vitriolated silver was dissolved, and added to the Kilburn water, 

 previously impregnated with pure nitrous acid, to effect a solution of the earthy 

 particles contained in it: the silver combined with the muriatic acid in the water, 

 and formed a luna cornea. But Mr. S. does not estimate the quantity of the acid 

 in the water from this experiment, which is liable to deceive, as well as the pre- 

 ceding. This will appear on comparing the result with the real quantity of vitro- 

 lic acid, as given in the contents of the water, annexed to these experiments. — 

 Exper. 14. A quantity of the Kilburn water having been gently evaporated to 

 dryness, a powder remained ; some of this being triturated with vegetable alkali, 

 there was no smell of volatile alkali perceived. — Exper. 15. A little of the powder 

 having been mixed with tartar, and thrown into a red hot crucible, no detonation 

 happened : of course nitre was not one of the constituent parts. 



Exper. l6. — On moistening a little of the powder with pure and concentrated 

 vitriolic acid, there arose muriatic vapours ; a proof there were no salts formed 

 with the nitrous acid existing in this water. The Kilburn water therefore con- 

 tains fixed air, hepatic air, earthy neutral salts, vitriolated and muriated neutral 

 salts, calcareous earth, magnesia, selenite, and a very little iron. These com- 

 f)onent parts of this mineral water appeared on the addition of reacting substances; 

 and with this guide he proceeds to the analysis. He begs however first to men- 

 tion another experiment or 1, relative to the effects of this water. Two quarts of 

 the fresh drawn water having been successively drank, operated gently down- 

 wards, but at the same time affected the head a little. This species of intoxica- 

 tion was however not produced, if the water had been freed from its hepatic air. 

 The celerity of the pulse was but little increased by it ; yet the following experi- 

 ment will prove that it pervaded the whole system, and affords a very strong 

 argument in favour of its efficacy. A small plate of silver was placed under the 

 arm, in contact with the skin, and thus worn for some hours without being 



