24 GRAHAM LUSK 



Only Black, professor of chemistry at Edinburgh and the discoverer 

 of "fixed air," saw the truth. Lavoisier wrote to Black on November 1-'!, 

 1790, a letter (Richet, (p) 1887) composed six months after the reading <>f 

 his last memoir to the Academic des Sciences. He concluded the letter 

 with the truest French courtesy : "It is only right that you should be the 

 first to be informed of progress in a field which you opened and in which 

 we all regard ourselves as your disciples. We do the same kind of 

 experiments and I have the honour to communicate to you the results of 

 our recent discoveries. I have the honour to remain, with respectful 

 attachment, etc." 



And to this Black replied in 1791, "The numerous experiments which 

 you have made on a large scale and which you have so well devised have 

 been persued with so much care and with such scrupulous attention to 

 details that nothing can be more satisfactory than the proofs you have 

 obtained. The system which you have based on the facts is so intimately 

 connected with them, is so simple and so intelligible, that it must become 

 more and more generally approved and adopted by a great number of 

 chemists who have long been accustomed to the old system. . . . Having 

 for thirty years believed and taught the doctrine of phlogiston as it was 

 understood before the discovery of your system, I for a long time felt 

 inimical to the new system which represented as absurd that which I had 

 hitherto regarded as sound doctrine, but this enmity which springs only 

 from force of habit has gradually diminished, subdued by the clearness 

 of your proofs and the soundness of your plan." 



In reading of the overthrow of the old doctrine of the fire principle 

 phlogiston one must feel a throb of the impending horror of the French 

 Revolution when one considers the statements of Marat written in 1791. 

 Marat at one time had declared that a flame, when placed in a confined 

 vessel, went out because the heat of the flame suddenly expanded the air, 

 causing such a pressure on the flame that it was extinguished. Lavoisier 

 refuted this doctrine. Marat, "L'Ami du People," under the title "Mod- 

 ern Charlatans," published the following: "Lavoisier, the putative 

 father of all the discoveries that are noised about, having no ideas of his 

 own, snatches at those of others, but having no ability to appreciate 

 them, he quickly abandons them and changes his theories as he does his 

 shoes." Certainly words of unqualified, contemporaneous disapproval ! 



Lavoisier's new system of salts and oxids led him to forecast the 

 discovery of sodium and potassium, for in his "Elements of Chemistry" 

 (Lavoisier, (m) 1799) he wrote, "It is quite possible that all the substances 

 we call earths may be only metallic oxids irreducible by any hitherto 

 known process." A eulogist of Lavoisier has likened this to the vision of 

 Copernicus before Galileo's invention of the telescope. 



Lavoisier had now progressed so that he was able to lay the funda- 

 mental basis of modern chemical physiology. Thus, in 1785, he stated 



