( 71 ) 



" Is it then true, that the exercise of all the social virtues, the rendering of 

 important services to one's country, a career usefully employed for advancing the progress 

 of the arts and extending the boundaries of human knowledge, do not suffice to preserve 

 one from a sinister end, and to avoid perishing on the scaffold like a culprit 1 " 



These are the words written by Lavoisier a few days before his 

 execution. 



There was born at Paris on August 26th, 1743, one who made the 

 name of Lavoisier immortal. He was educated at first for the law, but 

 soon natural science attracted him, and he studied botany under 

 B. de Jussieu and chemistry under Rouell. Like another of his 

 compatriots — CI. Bernard— and many men of science, he composed a 

 drama. He was admitted to the Academy of Sciences on June 1st, 

 1768 (a3t. 25). He married in 1771, and all went well until there 

 came with awful suddenness his tragic end. We pass over here his 

 connection with Le Ferme General, and all that this connection meant 

 to him. How strange are the events of history ! Madame Lavoisier in 

 1805 married Benjamin Thompson, better known as Count Rumford 

 (died 1814), but after four years "de luttes et de recriminations, une 

 separation a l'aimable eut lieu en 1809." Madame Lavoisier herself 

 died in 1836, set. 78. 



Priestley was a slave to the phlogistic theory. Lavoisier in 1775 

 published his fundamental paper On the nature of the Principle which, 

 combines with Metals daring Calcination. He found that a metal 

 took up something — in fact, gained weight — a fact which had been 

 recorded by Mayow long ago. The converse was true : a metallic 

 oxide, in becoming a metal, gave up something to the air. He had, 

 in fact, discovered oxygen, and thus became the creator of modern 

 chemistry. Priestley had prepared " dephlogisticated air " in 1754, 

 and in 1777 Lavoisier called this air respirable air, " vital air," or 

 " acidifying principle " or in its Greek form " oxygene." On May 3rd, 

 1777, he published his Experiments on the Respiration of Animals 

 and the changes which take place in the air passing through their 

 lung, and two other papers on the same subject with Seguin in 1789 

 and 1790. We need not pursue the matter here ; it is known to all. 

 Lavoisier may also be said to have founded thermo-chemistry and 

 calorimetry. With De Laplace in 1780, he published his famous me- 

 moir Sur la Chaleur. Respiration was a combustion, but not of carbon 

 only, for in his paper on " changes of the air during respiration," 

 Alterations qiteprouve I'air respire (read at Soc. de M^d. in 1785 

 and not at the Academy) — containing an exact determination of the 

 amount of oxygen which disappears and carbon dioxide expired, he 

 found that all the oxygen which disappeared was not replaced by 

 carbonic acid. We have already referred to this diminution in the 

 volume of expired air, when speaking of the work of Mayow. How 

 the combination of oxygen with the carbon on the one hand and the 



