Th’ eternal snows appear already past,
And the first clouds and mountains seem the last,
But, those attained, we tremble to survey
The growing labours of the lengthen’d way.
Th’ increasing prospect tires our wand’ring eyes,
Hills peep o’er hills, and Alps on Alps arise.
On the 14th of July, 1791, there occurred a serious riot at Birmingham, where Priestley was at that time settled as a Dissenting minister. On that day a banquet was being given in honor of the French Revolution, those who organized this feast being in large measure Episcopalians. There were numerous fraudulent cards of invitation which, rumor said, were issued by Priestley. On the occasion itself numerous toasts were offered in which sentiments antagonistic to those generally entertained by the originators of the feast, were expressed. As the festival progressed the crowd became more and more excited and everybody seemed to be imbued with the idea that in some way or other Priestley was mixed up in the matter. The truth was, however, he had nothing whatever to do with it, was not present at the banquet, and even did not know that such a feast was being given. Nevertheless, the crowd would not listen to reason, and insisted that Priestley was the cause of the whole trouble. Accordingly they secured lighted torches and hastened to Priestley’s house which was located about half a mile from the city limits, and proceeded to set it on fire. Thus were destroyed, in the course of a few minutes, all his books, all his valuable scientific apparatus, all the registers of experiments covering a period of eleven years of unremitting toil. Priestley, who was then nearly seventy years old, lost practically everything that he possessed. For three days the rioting continued, many of the houses of Priestley’s friends being also destroyed by fire. Even the daily newspapers asserted that among Priestley’s papers were found evidences showing that a great conspiracy existed,—but for what evil purpose it was not stated. Insults of all sorts were heaped upon the innocent man, until finally he was compelled, by the situation of affairs in Birmingham, to leave the country. Fortunately for him, Priestley’s brother-in-law left him in his will the sum of £10,000 and also an annuity of £200. Thus provided for, Priestley left England in 1794 and settled in Pennsylvania. His death occurred in 1804.
Antoine Laurent Lavoisier was born in 1743 at Paris, and at an early age displayed a fondness for serious scientific studies. In 1768, although he had attained only his twenty-fifth year, he was chosen a member of the French Academy of the Sciences; and a very short time afterward he received the appointment of Fermier Général (Government Collector of Taxes), an appointment which showed how highly he was esteemed for his ability as well as for his integrity. At first, Lavoisier, like nearly all his contemporaries, accepted Stahl’s phlogiston doctrine and his views with regard to animism (see pp. 432 and 433 of my work entitled: “The Growth of Medicine”); but gradually he entertained more and more serious doubts with regard to their correctness, and finally he came out boldly as an opponent of these doctrines. The experiments which he himself made, as well as those which were carried out by other scientists of the same period, forced him to conclude that, in all chemical processes, no such thing as an actual creation of something new takes place, nor is anything ever lost. This truth, he claimed, applies as well to living beings as to inanimate objects. In the middle of the eighteenth century the treatises on chemistry did not acknowledge this teaching as true. Vauquelin, for example, pointed to what he believed to be a fact, viz., that animals actually produce lime, inasmuch as hens—so he claimed—produce more lime than they ingest with their food. Lavoisier’s remarkable experiments showed that Stahl’s doctrine of animism, as well as the phlogiston theory, was untenable. Stahl maintained, for example, that there exists in all combustible bodies a special element which is set free during the combustion of such bodies, and to this element—as I have already stated on a previous page—he gave the name of “phlogiston.” Lavoisier, on the other hand, made it clear that combustion represents simply the combination of the two elements, carbon and oxygen; and at the same time he showed that the act of respiration in animals is a species of combustion, in the course of which oxygen combines with certain elements of the body to form water and carbonic acid. He did not, however, rest satisfied with these results, but—aided by Seguin—pushed his experiments to the point where he demonstrated the quantities of gas expired both by man and by animals; thus greatly increasing our knowledge of the phenomena of life.
Furthermore, Lavoisier was also the discoverer of a method of analysis (still employed to-day) by means of which it is possible to demonstrate the important fact that all organic bodies are composed of carbon, hydrogen and oxygen, sometimes in association with azote (lifeless matter). In a word, he brought physiological chemistry to such a stage of perfection that his successors have been able only to make additions to the facts which he discovered, but not to alter them in any essential respect.