1820.] Scientific Intelligence. 227 



another jar, in which the nitrous gas was converted into protox- 

 ide of azote by moist iron, yet the iron wire yielded no air 

 bubbles during tiie whole time the process lasted. 



II. Phosphorous Acid. 



Berzelius has endeavoured to prove, in a paper which he pub- 

 lished some years ago, that the oxygen in phosphorous acid is to 

 that in phosphoric acid as the number 3 to ii. The compositioa 

 of the two acids, according to his view of the subject, is as 

 follows : 



Phosphorous acid composed of. . . 2 phosphorus + 1-5 oxygea 

 Phosphoric acid 2 + 2"5 



so that, in order to obtain whole numbers for oxygen, we must 

 make the weight of an atom of phosphorus 4, and consider 

 phosphorous acid as a compound of one atom phosphorus and 

 three atoms oxygen, and phosphoric acid as a compound of one 

 atom phosphorus and five atoms oxygen. 



A set of experiments which I published some years ago seem 

 to me to demonstrate the constitution of these two acids in a 

 satisfactory manner. Phosphuretted hydrogen gas is of the 

 specific gravity 0*9022. It is composed by weight of 



Phosphorus 12 or 1*500 



Hydrogen 1 0*125 



Therefore, if it be a compound of an atom of phosphorus and aa 

 atom of hydrogen, an atom of phosphorus must weigh 1*5. This 

 gas for complete combustion requires either its own volume of 

 oxygen gas, or l-i time its own volume. Now this gas consists 

 of one volume of hydrogen gas combined with one volume of the 

 vapour of phosphorus, and both condensed into one volume ; 

 therefore the hydrogen in this gas will require half a volume of 

 oxygen gas to convert it into water ; so that the phosphorus ia- 

 a volume of phosphuretted hydrogen gas is capable of combining 

 either with half a volume of oxygen gas, or with a whole volume. 

 In the first place, phosphorous acid is formed, and in the second 

 place phosphoric acid. By these experiments (which were made 

 with the utmost care) it is demonstrated, I conceive, that phos- 

 phoric acid contains just twice as much oxygen as phosphorous 

 acid combined with the same weight of phosphorus. These 

 experiments are much more decisive than those of Berzelius, and 

 they have the advantage of being much more easily made;. AH 

 that is necessary is to procure phosphuretted hydrogen gd3 in a' 

 state of purity. 



The specific gravity of phosphuretted hydrogen gas being 

 0*9022, and hydrogen gas not altering its bulk when it is con- 

 Terted into phosphuretted hydrogen gas, it is obvious that if we 

 subtract the specific gravity of hydrogen gas from that of phos- 



p 2 



