102 An ANALYSIS of 



vitriolic acid, compared with that of w^ter, was as 1798 to 1000, 

 in a temperature of heat equal to 60 of Fahrenheit. When 

 I had ufed it on former occafions, I diluted fome of it, with 

 four times its weight of diftilled water, and ufed this mixture 

 in place of the pure acid, that I might the more readily portion 

 it into fmall dozes ; but on this occafion, I made a mixture of 

 it, with about 100 times its weight of diftilled water; and ef- 

 faying this mixture afterwards, with great attention, I found 

 that 112 grains of it faturated one grain of the pure alkaline 

 part of the alkali of tartar, and 171.55 grains were required 

 for the faturation of one grain of the pure or cauftic part of the 

 foffil alkali. 



With this largely diluted acid, the ftrength of which was 

 thus afcertained, I began to inveitigate the quantity of alkali 

 in the Iceland waters. I gave a pale purple or blue colour to a 

 portion of the Rykum water, by adding a few drops of an in- 

 fuiion of litmus, the bluifh purple of which became more 

 blue when mixed with this alkaline water, and I began to add 

 very gradually fome of the largely diluted vitriolic acid, ex- 

 peeling to fee the colour change to a reddilh purple, when the 

 alkali became completely faturated. This method, however, 

 did not fucceed fo well as I had fuppofed ; for although I 

 changed the colour to a reddifh purple, or even to a pure red, 

 by adding an exceeding fmall quantity of the diluted acid, the 

 red thus produced was not permanent. Next day, I found it 

 returned again to the blue, and requiring a new addition of 

 acid ; and this happened fo often, after repeated additions of 

 acid, that this procefs appeared very tedious, and fcarcely ca- 

 pable of being brought to a precife limit ; for in proportion as 

 I continued the procefs the longer time, or had made the more 

 numerous additions of acid, the time neceffary for the return of 

 the colour from red to blue was always the longer, and at laft 

 was no lefs than feveral weeks. 



These 



