in the Isle of Wight, 221 



§ V. Gaseous Contents of the Water, 



A quantity of the water measuring ten cubic inches, being boiled 

 briskly over mercury, the gas given out, together with the air 

 contained In the apparatus, was received In a graduated tube ; on 

 admitting cauetic alkali into the tube, one-tenth of a cubic inch of 

 gas was absorbed. It appears therefore that one hundred cubic 

 Inches of the water contain one cubic Inch of carbonic acid gas, 

 which is equivalent to about three-tenths of a cubic inch to each 

 pint. The water was uncorked at the moment of being examined, 

 but I had not an opportunity of ascertaining the quantity of gas. 



§ VI. Evaporation of the Water ^ and Estimation of the S^uantity 

 of solid Ingredients, 



1. Sixteen ounces of the water by measure, being evaporated 

 down to a soft mass over a lamp, and afterwards desiccated In a 

 drying apparatus at the heat of 180%* the solid mass weighed 

 eighty-six grains. During the evaporation the same appearances 

 were observed as have been already related (In § III., D,) and the 

 dry saline mass assumed a pale greenish colour. On standing In the 

 air, it slightly deliquesced, and its colour became somewhat darker. 

 This saline mass, though slowly evaporated, never assumed a distinct 

 crystalline appearance. 



* This is the heat I have usually employed for desiccation, because it is that which Is 

 obtained by the water- bath which I use, and can scarcely be raised higher by that appa- 

 ratus. By a heat of 180° however, I generally mean some intermediate point between 

 170° and 180° for it is imposible to regulate the temperature with perfect accuracy. 



