42 Dr Davy on the Use^ of (he Microscope. 



phosphate of lime, according as the one or the other predo- 

 minates, will be the proportion in which the one or other 

 aspect will be imparted to the mixture ; and, should phos- 

 phate of magnesia be present in admixture with alumina 

 and phosphate of lime, it may easily be detected under the 

 microscope. Before the addition of the acid, its well-marked 

 crystals will be seen, which after that addition will disappear. 

 As my object is chiefly to draw attention to the applica- 

 tion of the microscope as an aid to chemical research, the 

 instances adduced, I trust, will be considered sufficient in the 

 way of illustration. Very many more might be given, but 

 they would be out of place on this occasion. Were they 

 minutely detailed they would be tedious ; and were they only 

 briefly adverted to, practically they would be useless. The 

 subject, to have justice done to it, would require a distinct 

 treatise, founded on laborious research, and giving the re- 

 sults of such research ; and it is one, of which it may con- 

 fidently be predicated, that it would amply repay whatever 

 time, whatever labour, might be expended on the under- 

 taking. 



In conclusion, this, it appears to me, may justly be said in 

 commendation of the microscope, in all its applications, that 

 its tendency is equally to facilitate and increase accuracy of 

 observation, and hence to remove vagueness and give pre- 

 cision of views, and, at the same time, to add wonderfully 

 to the interest of inquiry, and to extend its sphere, — in this 

 respect having an influence in relation to subjects for chemi- 

 cal research resembling that of the most powerful telescopes 

 in relation to the objects of astronomical research, both con- 

 ducing, the one hardly less than the other, by the phenomena 

 they display, to excite in the mind of the philosophical in- 

 quirer feelings of admiration, and of awe, and not less of 

 humility. 



Baebadoes, January 19, 1846. 



