344 Dr. Murray on the Chemical Constitution of [Nov. 



33ut when the contents of the retort, which, for some time, have 

 "been kept comparatively cool by the escape of condensible fluids, 

 become more intensely heated, ammonia' is either not formed, 

 or, if formed, is decomposed again into azotic and hydrogen 

 gases, both of which may be traced in the aeriform products of 

 the advanced stages of distillation. As a matter of practice, it 

 is certainly desirable that the azote existing in coal should enter 

 into the composition of a condensible fluid rather than that it 

 should escape in a gaseous state ; for it is an impurity which, 

 when once mingled with the combustible gas, cannot be removed 

 t>y any known method, and must materially impair its illuminat- 

 ing power. That such an effect must result from its presence 

 may be inferred from the experiments of Sir H. Davy, who 

 found that an explosive mixture of carburetted hydrogen and 

 common air was deprived of its combustibility by being mixed 

 with one-sixth of its bulk of azotic^ gas.* 



(To be continued.) 



Article IV. 



Qbservations on the Relation of the Laic of Definite Proportions 

 in Chemical Combination, to the Constitution of the Acids, 

 Alkalies, and Earths. By John Murray, M.D. Sec. »kc. 



(Concluded from p . 29-1.) 



The composition of the acids, of which phosphorus is the 

 base, is so imperfectly determined, and the most recent experi- 

 mental researches are so much at variance in their results, that 

 scarcely any satisfactory application of a principle can be applied 

 to them. There is some reason to believe that the three acids 

 which appear to be of definite composition, the hypophospho- 

 tous, phosphorous, and phosphoric acid, contain oxygen in 

 proportions affording the multiples 1, 2, 4. The intermediate 

 multiple of 3 is probably to be found in the combination which 

 is established of phosphorous acid acting on a base, conformable 

 to the view illustrated in the analogous case of sulphurous acid, 

 the acid receiving the oxygen of the base, and a ternary com- 

 pound being formed, in which the whole oxygen and the radical 

 of the base observe the due relation to the radical of the acid. 

 And from the quantity of base which phosphorous acid must 

 .saturate, this additional proportion of oxygen will be precisely a 

 aniiltiple of that with which phosphorus combines. Phosphoric 

 acid appears to be formed in the combustion of phosphorus iu 

 oxvg-en, and must, therefore, be admitted to exist as an insulated 



• On the Safety Lamp, p. 80. 



