256 Dr. Andrew Steel [April 



It is very difficult to make experiments of this nature 

 with absolute accuracy : allowing a very small error to have 

 been committed, it would bring it exactly to 3; to which, 

 however, the experiments approach so nearly, as we think 

 to warrant the conclusion, that the atomic proportion is 

 really the point at which the greatest condensation takes 

 place. So that, we have, at least, two definite compounds 

 of alcohol and water, possessing distinct properties. 



The first is a compound of 



4 atoms alcohol . .. . 11*5 

 1 „ water .... 1-125 



6-250 * 

 From the above, with the assistance of Mr. Gilpin's 

 table, we have computed the following, exhibiting the 



* The condensation or diminution in volume which takes place, almost with- 

 out exception, on mixing substances of different specific gravities with each 

 other, has been usually explained by writers on the subject, as the result of a 

 powerful chemical affinity between them. 



If we admit the ultimate atoms of all bodies to be spherical, by far, certainly, 

 the most plausible doctrine that has been advanced, and in favour of whiclv indeed 

 this very phenomenon of condensation, is perhaps, the most decisive proof that 

 can be adduced, there is no need of any affinity for its explanation. 



The amount of the diminution in volume, depends on the specific gravity, or 

 more correctly, on the difference in size of the ultimate atoms of the substances, 

 and is in fact, the mere mechanical effect that must be produced by mixing 

 together spherical atoms of different bulks, and is well illustrated by the following 

 simple but very striking experiment : 



Lead drops of different sizes (Nos. 4, and 10,) were taken as the representa- 

 tives of two substances of unequal sized atoms. 



Into a graduated glass tube, 50 measures of No. 10, and 50 measures of No. 4, 

 were introduced. Their bulk in this state was of course, exactly 100 measures, 

 on being well shaken so as to mix them thoroughly, their bulk was reduced to 

 95 measures, so that a concentration of 5 per cent, had taken place, this amount 

 was found to vary with the proportions employed. 



It maybe objected to this explanation, that some substances on mixture actu- 

 ally increase in volume, a fact, if true, quite incompatible with the above views. 

 We believe, however, that more correct experiments will do away with the 

 greatest number, if not the whole, of these exceptions. 



The subject seems worthy of attention, as likely to throw great light upon some 

 of our chemical theories, even from the above simple experiment of the lead drops, 

 we think some inferences of the highest importance to atomic chemistry may be 

 deduced. 



