36 Improvements in Physical Science (Jan, 
Bhosphor yp. sé: laia, -yhraisis sae renters averaged OO 
Ong enigiages cp PUI Tee es AN ise eis, Sega Ce A 
Phosphoric acid, which is obtained by the rapid combustion of 
phosphorus, has been long known. According to the analysis of 
Dulong, it is composed of 
Phosp lings o cyan: a2» o¥e a's! ajo fos =o oe, LOU 
OXYSeI et tia deans ss Mode saat Oa.) 
This new acid discovered by M. Dulong is a chemical fact of con- 
siderable importance. If his hypophosphorous acid prove a combi- 
nation of pkosphorus and oxygen, without any hydrogen, it will 
oblige us to double the weight of an atom of phosphorus. I con- 
sider the method which I employed to determine the composition 
of phosphorus and phosphoric acids in my paper on phosphureted 
hydrogen gas as susceptible of much greater precision than apy 
mode hitherto tried of analyzing the acids directly. On that account 
I conceive that the numbers which 1 have given are much nearer 
the truth than those of Dulong. The only part of my experiments 
liable to uncertainty is the specific gravity of the phosphureted 
hydrogen gas; for the quantities of gas which I weighed (25 cubic 
inches) were too small to give results of very great accuracy. Never- 
theless I do not believe that I could fall into any great error, as ft 
was at considerable pains to be as near precision as possible. If we 
correct Dulong’s analyses by my experiments, we shall have the 
acids of phosphorus as follows :— 
Phosphorus. Oxygen, 
Hypophosphorous'acid ...... 100 + 33°3 
Phosphoreus acid .......... 100 + 666 
Phosphoric acid .........-.. 100 + 133:3 
I omit the phosphatic acid, because, even according to M. 
Dulong’s own views, it cannot be considered as a simple combina- 
tion of phosphorus and oxygen. Jf the hypophosphorous acid be a 
binary compound, the weight of an atom of phosphorus will be 3 ; 
but it would be premature to make any alteration in that weight till 
M. Dulong has published the experiments, which he promises, in 
order to investigate whether or not hydrogen be one of its consti- 
tuents. Should this hypothesis be well founded, it must receive a 
new name, and be considered under quite a different point of view. 
Professor Berzelius, one of the most accurate chemists of the 
present day, and certainly the most active, has lately published an 
elaborate set of experiments on the composition of phosphoric and 
phosphorous acids. To determine the composition of phosphoric 
acid, he digested a given weight of phosphorus in a solution of gold 
in aqua regia, evaporated to dryness, and re-dissolved in water, 
0-754 of phosphorus reduced 7°93 of gold to the metallic state; or 
one part of phosphorus to be converted into phosphoric acid unites 
with as much oxygen as is capable of combining with 10°517 parts. 
