on [Gaseous] Supersaturated Solutions, 185 



to the required strength, and made me independent of the va- 

 riations which constantly occur in spring-water*. By the use 

 of small quantities of the powder and the before-mentioned solids 

 immersed in the water, as soon as it became clear the action was 

 very decided, so that decreasing quantities of the powder were 

 sufficient to cause the solids to be covered with innumerable 

 bubbles as soon as they were immersed. A fuller impregnation 

 of the water produced a lively effervescence. The results are so 

 beautiful as to leave nothing to be desired. Moreover the "car- 

 bonic acid remains a remarkably long time in the water. In 

 less than two cubic inches of carbonic-acid water, brass and silver 

 wires acted after twenty-four hours and produced an abundant 

 separation of bubbles. 



Since, by frequent repetitions of these experiments, the same 

 results were always obtained, and as I had bestowed the greatest 

 care on the cleansing of the submerged solids, I am fully con- 

 vinced that solids made perfectly clean, coming into contact 

 with gas-impregnated water, is a necessary condition for the 

 unequivocal production of the phenomena in question. This is 

 in direct opposition to the hitherto received view, according to 

 which unclean, and especially dusty surfaces, produce the sepa- 

 ration of the bubbles in question. This view does not seem to 

 have been submitted to rigid proof, but rather to have been sup- 

 ported by a solitary experiment. If a given surface, such as a 

 silver wire, a glass rod, &c, be submitted to the action of a small 

 flame of spirits of wine, such a surface will scarcely act, or not 

 act at all, in separating gas. Hence it has been concluded that 

 all kinds of organic substances contracted by exposure to the air 

 were thus burnt off from the surface so as to leave it perfectly 

 clean. This conclusion, however, follows so little from the pre- 

 mises, that the flame produces only a change in the covering and 

 converts it into carbon or ash. This consideration has led me 

 to inquire further into the matter ; and the following are the 

 results : — 



A carefully cleaned glass rod was for some time moved over a 

 small flame of spirits of wine, after which nothing could be seen 

 upon its surface; but when it was drawn with slight pressure 

 between the folds of a clean linen cloth, a frictional impediment 

 was plainly felt, even producing a faint noise when the pressure 



* These changes are really very great. My experiments with spring- 

 water were for the most part carried on in summer; and I was very much 

 surprised, on resuming them in autumn, to find the same water of no use. 

 In summer the fermentation of the moist constituents of the soil is most 

 active ; we might therefore presume that the gaseous contents of spring- 

 water at that season consist chiefly of carbonic acid ; only the water drawn 

 in autumn gave a precipitate with barvta- water. The solid contents of the 

 water of this place are exceedingly small. 



