Miscellanies. 151 



much as the hard. The author made numerous experiments of this 

 description. The absorbent iiature of the leaves renders it difficult 

 to compare, with accuracy, waters differing little from each other. 



The effect of pure water, he says, is very near to that of any nat- 

 ural water, containing carbonate of soda, but the soda is supposed a 

 little to increase the quantity taken up, as well as the sensibility of 

 the palate. — Jour, of Royal Inst. Vol. I. p. 42. 



6. On the limits of vaporization, by M. Faraday, F. R. S. — 

 A series of experiments has been performed by this distinguished 

 chemist to ascertain whether there are actually definite limits to the 

 force of vaporization. Even when water becomes ice, the ice evap- 

 orates, and there is no cold either natural or artificial, so intense as 

 entirely to stop the evaporation of water, or in the open air to pre- 

 vent a wet thing from becoming dry. 



The question which the ingenious author sought to determine was 

 whether, as appears to be the opinion of Davy, Dalton, and others, 

 every substance, (even the most solid) has an atmosphere of its own 

 nature about it, and diffused in its own neighborhood. This atmos- 

 phere, in the case of fixed substances, as the earths and metals, might, 

 it was. thought, be so feeble as to be quite insensible even by extraor- 

 dinary examination, and yet, rising into the atmosphere, may produce 

 peculiar results. 



Some former investigations of the author induced him to suppose 

 that we possess a great number of substances which are perfectly fixed, 

 and no portion of whose substance rises into vapor under any ordina- 

 ry circumstances of temperature. 



In September, 1826, several stoppered bottles were made perfect- 

 ly clean, and several wide tubes, closed at one extremity, so as to 

 form smaller vessels capable of being placed within the bottles, were 

 prepared. Selected substances were then put into the tubes, and 

 solutions of other selected substances in the bottles ; the tubes were 

 placed in the bottles so that nothing could pass from one substance to 

 the other, except by vaporization. The stoppers were introduced, the 

 botdes tied over carefully, and put away in a dark safe cupboard, 

 where they remained undisturbed for four years. The most impor- 

 tant results were the following. 



No. 1. Bottle — clear solution of sulphate of soda with a drop of 

 nitric acid : tuhe — crystals of muriate of baryta. One half the 

 water passed into the tube, and formed a solution of muriate of ba- 

 ryta. No trace of sulphate of baryta in either. 



