76 Roy at Institution. 



belonged, but which likewise promised to enlighten the 

 whole philosophy of terrestrial nature. 



In treating of the substances which undergo chemical 

 changes, he said, he should first consider radiant or ethe- 

 real matter, those which are kiiown only in motion, or by 

 their effects. He said, he should discuss particularly the 

 polariti/ of light advanced by Newton, and confirmed by 

 the late experiments of Makis. The solar rays produce 

 that light and chemical effects, and there is an analogy be- 

 tween the powers of the two solar beams and electricity ; 

 and crvstailine bodies have certain relations to light, like 

 ■ those of different electrified surfaces; and from new inves- 

 tigations on this subject, the Professor said, he anticipated 

 a moYe intimate connexion between chemical and mecha- 

 nical philosophy. 



He divided ponderable nndecomposed substances into 

 two classes, empvreal and inflammable supporters of com- 

 bustion and Gon)bu3lible bodies; and from ten different 

 combinations deduced all '.he pha;nomena of composition. 

 They unite, he said, according to uniform' laws ; form 

 definite compounds, generally crystallized, and which 

 may be represented bv numbers resulting from the addition 

 of the numbers representing their elements. As in the 

 system of the Heavens, gravitation and the projectile force 

 acting; according to constant laws produce tbe regular and 

 harmonious motion of the planets, so in the terrestrial cy- 

 cle of events, the repulsive and attractive powers of matter 

 are in uniform operation, occasion a series of events flow- 

 intr in a happy order, and constantly subservient to the 

 purposes of life. 



Mr. Davy concluded his lecture by some observations 

 on the uses of the science, and the advantages resulting 

 from the study. From the earliest aera of society, he said, 

 when metals were produced from rude ores to the know- 

 ledge of the bleacfiing liquor, chemistry had been con- 

 stantly subservient to cultivation and improvement in the 

 manulacture of porcelain and glass, in the arts of dyeing 

 and tanning, and has added to the elegancies, refinements, 

 and comforts of life. In its application to medicine, it 

 has removed the most formidable of diseases ; and as lead- 

 ing to the discovery of gunpowder, it has changed the in- 

 stitutions of society, and rendered men iiiorc independent 

 of brutal strength, les=; personal and less barbarous. There 

 is, said Mr. Davy, adoul)le source of interest in chemistry, 

 that whilst it is connected with the grand operations of na- 

 ture, it is likewise subservient to the most common pro- 

 cesses 



