208 On the Limits of Vaporization. [1830. 



by reason of this peculiarity, have any sensible degree of vola- 

 tility, in conjunction with water or its vapour, conferred upon 

 them at ordinary temperatures, that the following experiments 

 were made. It is well known that a theory of meteoric stones 

 has been founded on the supposition that the earthy and metallic 

 matter found in them had been raised in vapour from similar 

 matter upon the earth's surface ; which vapours, though ex- 

 tremely attenuated and dilute at first, gradually accumulated, 

 and by some natural operation in the upper regions of the atmo- 

 sphere became condensed, forming those extraordinary masses 

 of matter which occasionally fall to us from above. The theory 

 has in its favour the remarkable circumstance, that, notwith- 

 standing many substances occur in meteoric iron and stones, 

 yet there is none but what also occur on this our earth* ; and 

 it also has a right to the favouring action of water, if there be 

 such an action ; because vaporization is one of the most import- 

 ant, continual, and extensive operations that go on between the 

 surface of the globe and the atmosphere around it. 



In September 1826, several stoppered bottles were made 

 perfectly clean, and several wide tubes closed at one extremity, 

 so as to form smaller vessels capable of being placed within the 

 bottles, were prepared. Then selected substances were put 

 into the tubes, and solutions of other selected substances into 

 the bottles : the tubes were placed in the bottles so that nothing 

 could pass from the one substance to the other, except by way 

 of vaporization. The stoppers were introduced, the bottles tied 

 over carefully and put away in a dark safe cupboard, where, 

 except for an occasional examination, they have been left for 

 nearly four years, during which time such portion of the sub- 

 stances as could vaporize have been free to act and produce 

 accumulation of their specific effects. 



No. 1. The bottle contained a clear solution of sulphate of 

 soda with a drop of nitric acid, the tube, crystals of muriate 

 of baryta. One half or more of the water has passed by eva- 

 poration into the tube, and formed a solution of muriate of 



* This very striking circumstance does not prove that aerolites in any way 

 originate from our planet ; but then, if we could by other arguments deduce 

 that they were extraneous, it would lead to the conclusion that the substances 

 which have been used in the construction of this our globe, are the same with 

 those which have been used extensively elsewhere in the material creation. 



