1830.] The Progress of Physical Discovery. 267 



only to chemistry, but to physiology, on account of their analogy with 

 the mysterious phenomena of the animal secretions. Two new vegetable 

 alkalis, called strychnine and brucine, were, in this year, recognized by 

 Pelletier and Caventon ; a third, by Boullai, in the poppy of the Levant ; 

 and a fourth, by Vauquelin, in the Daphne-mezereum, which, together 

 with morphine, of which we have spoken, form an important acquisi- 

 tion to chemistry. They are composed of oxygen, hydrogen, and car- 

 bon, and are a striking instance of the opposite means by which nature 

 arrives at similar effects. Potash soda, and other mineral salifiable bases, 

 are metallic oxides ; ammoniac is a combination of hydrogen and nitro- 

 gen ; and here are saKfiable bases composed of merely hydrogen, carbon, 

 and oxygen, elements which enter into various other kinds of vegetables 

 which have no connection with alkalis. 



In 1820, our countryman, Mr. Porrett, in his Researches upon Prus- 

 sian Blue, and its Combinations, discovered that the salt, known as 

 triple prussiate of potash, was composed of potash and a peculiar acid 

 which combines the elements of prussic acid and oxide of iron. M. 

 Roubiquet subsequently found that this acid contains no oxygen, and 

 that the iron is consequently in it in a metallic state ; he considered it as 

 made of hydrocyanic acid and cyanure of iron, and that its union with 

 peroxyde of iron is Prussian blue. In this year also, MM. Pelletier 

 and Caventon made a discovery of the highest importance in the class 

 of vegetable alkalis already mentioned, viz., the febrifuge principle of 

 quinquina, which is found in the colouring matter of the quinquina, 

 united to an acid which renders it soluble. It had, indeed, been per- 

 ceived before by Gomes, a Portuguese chemist, yet he was entirely 

 ignorant of its alkaline nature. This principle exists in the grey quin- 

 quina, and is called cinchonine ; the yellow quinquina contains a prin- 

 ciple slightly different, now in such familiar use under the name of 

 quinine ; and the red quinquina contains both principles in a considera- 

 ble proportion. If the Jesuits have immortalized their order, as it is 

 said, by the importation into Europe of Peruvian bark, these French 

 chemists have reaped no less honour by bringing to light, substances, 

 whose application to medicinal purposes has since become so valuable 

 and extensive. 



In analyzing various plants of the colchican species, Pelletier and 

 Caventon, in this year, detected another alkaline substance, which they 

 named veratrine, making the list of vegetable alkalis now contain seven, 

 of which, four years ago, not one was known. 



The researches of M. Chevreul on animal bodies produced an elabo- 

 rate report in 1821. We have before alluded to his steatine and elaine 

 principles, of the combination of which he considers organic bodies to be 

 the result, when united to each other, as an acid to an alkali, or a com- 

 burant to a combustible. If his observations should draw attention to 

 that chemical law, by which an energetic substance becomes able, by a 

 kind of force, to effect the formation of opposite substances with which 

 it unites, much light may. thereby be thrown on the physiology of living 

 bodies in this respect. 



The works of Crawfurd and Lavoisier had caused the physiologists to 

 revive the opinions held in the seventeenth century by Mayow and Willis, 

 which attributed animal heat generally to the fixation of the oxygen ab- 

 sorbed during respiration, or, in other words, to the combustion which 

 takes place in this act. M. Dulong, in 1822, by the aid of the caloro- 



2 M 2 



