134 Royal Instituiian. 



iTiical philosophy was to be erected ; and it should therefor 

 be constructed with care. Mr. Davy nientioTied that che- 

 mical attraction was the power by which different bodies 

 uniie with each other and form new and different substances; 

 that somebodies possess no chemical attraction, and others 

 exert it with different degrees of force; which he illusiraied bv 

 experiments. He said, the law of combination, or the unioti 

 bv chemical attraction, applied to all the different ponde- 

 rable forms of matter; fluids not only produce solid matter, 

 but sometimes likewise gaseous matter ; and gases aie 

 condensed into fluids or solids : he instanced the combi- 

 nation of aquafortis, or nitric acid, with alcohol; also ole- 

 fiant gas and chlorine ; likewise sulphureous acid gas wlih 

 ammonia; and proved, that as their forms and properties 

 were visibly changed, so likewise were their other sensible 

 qualities. He next referred to his introductory lecture, in 

 •which he meiuioned that bodies which attract each olher 

 unite in definite proportions. This law, said the Professor, 

 is perhaps the most important of our science, and admits 

 of elucidation by a number of experiments. He showed 

 the combinations of barytes and sulphuric acid, chlorine 

 and hydrogen, hydrogen and oxygen : they always unite 

 in definite proportions. Mr. Davy showed also some ex- 

 periments on the combination of muriatic acid gas with 

 ammonia. This experiment, he said, was irientioned lately 

 in a monthly publication, by Mr. Murray, to prove the 

 presence of water in muriatic acid gas; but the Professor 

 clearly proved, that the presence of water was owing to the 

 hygrometric qualities of the salt, which, when exposed to 

 the atmosphere for an instant; absorbs moisture directly ; 

 and he showed an experiment, in which, when muriatic gas 

 and ammonia were combined out of the atmosphere and 

 heated, not an atom of water could be procured frcMii ihem. 

 Nature acis by this fixed and immutable law ; and her ar- 

 rangements, said he, however diversified, follow a certain 

 order ; the circumstances of crystallization and definite 

 proportion form the alphabet by which her chemical lan- 

 guage is to be deciphered; and it is not composed of nu- 

 merous hieroglyphics, but of a few simple characters. Mr. 

 Davy said, that when two bodies combine in more than 

 one proportion, still their proportif^ns are definite, that the 

 second proportion is always a multiple or a divisor of the 

 first ; he instanced mercury, which combines with two 

 proportions of oxygen, the second oxide contains double 

 the quantity of oxygen of the first; also fluoric acid, 

 which combines with ammonia in two proportions, viz. 

 one in volume, and two in volume ; so thai the first con- 

 tains 



