BLACK. 5 



deriving from it their caustic quality; the common 

 belief (which gave rise to the term caustic) being that 

 lime obtained from the fire the quality of growing ex- 

 tremely hot, even to ignition when united with water. 

 But experiment soon corrected this idea ; for, having 

 exposed the caustic or quicklime to the air till it be- 

 came mild, he says, "Nothing escapes (meaning no 

 fire or heat) ; the cup rises considerably by absorbing 

 air." Another observation on the comparative loss of 

 weight sustained by chalk when calcined (in the fire), 

 and when dissolved in an acid, is followed by the ac- 

 count of a medical case, which the Professor knew to 

 have occurred in 1752. A third note follows, and 

 proves him to have now become possessed of the true 

 theory of causticity, namely, the expulsion of air, and 

 of mildness, namely, its absorption. The discovery 

 was therefore made as early as 1752 it was published 

 generally in 1754 it was given in its fullest details in 

 1755. At this time M. Lavoisier was a boy at school 

 nine years old when the discovery was made eleven 

 when it was published twelve when it was as fully 

 given to the world as its author ever delivered it. No 

 possibility therefore existed of that great man finding 

 out when he composed his great work that it was a 

 discovery of his own, as he did not scruple to describe 

 oxygen, though Dr. Priestley had first communicated 

 it to him in the year 1774 ; or that Black and he dis- 

 covered it about the same time, as he was in the habit 

 of stating with respect to other gases, with a convenient 

 degree of ambiguity just sufficient for self-defence, 

 should he be charged with unfair appropriation. Who 

 that reflects on the noble part which this great philo- 

 sopher acted, both in his life and in his death, can 

 avoid lamenting that he did not rest satisfied with the 

 fame really his due, of applying the discoveries in which 

 he had no kind of share, to the investigation of scien- 

 tific truths, as entirely the result of his extraordinary 

 faculty of generalization, and genius for philosophical 



