REPORT ON CHEMISTRY. 
153 
basic oxides. With ammonia also they combine without de¬ 
composition : their combinations with phosphuretted hydrogen 
are not known. 
o°. Its gaseous compounds with nitrogen, phosphorus, and 
arsenic.—These act in all cases as bases. In the case of am¬ 
monia this is well known. Serullas and Rose have shown it to 
hold also with phosphuretted hydrogen, and from analogy we 
infer the same of arseniuretted hydrogen. 
The composition of this group is such, that one volume of 
the compound contains one volume and a half ofhydrogen-f half 
a volume of radical, in the gaseous state. 
4°. Its compounds with carbon.— In these there exists still 
more hydrogen than in the third group, and they act more 
powerfully as bases. 
Hydrogen, therefore, seems to be the principle on which the 
basic property of very many compounds depends. It has also 
an analogy with oxygen in forming both acids and bases,—but 
with this difference, that while oxygen forms acids when pre¬ 
sent in large, and bases when in small quantity, hydrogen, on 
the contrary, forms bases when present in large, and acids only 
when combined in small quantity with electro-negative sub¬ 
stances. 
Water , maximum density of. —The question as to the tem¬ 
perature at which the density of water is a maximum, does not 
seem to be yet quite settled. De Luc first fixed it at 40° Fahr.; 
Sir Charles Blagden and Mr. Gilpin reduced it to 39° ; Dr. 
Hope’ s elegant method gave39 c, 5; Biot, in his Tables {Traite,\. 
p. 425), gives, by calculation, 38°T56 ; and the French, in fix¬ 
ing their standard weights and measures, adopted 40°. More 
lately, the elaborate researches of Hallsti om* fixed it at 39 0, 38, 
in which determination great confidence was placed. Prof. 
Stampfer 4 , of Vienna, has renewed the investigation with the 
adoption of new precautions. His method was to weigh a hol¬ 
low cylinder of known bulk, made air-tight, at about 66 ° Fahr., 
in water of different temperatures ; and to insure accuracy, he 
continued his weighings during a whole year, so as to have the 
temperatures of the water and surrounding air nearly alike. 
From a great number of results carefully corrected, he deduces 
38°*75 for the maximum density. MunckeJ also has made 
experiments on the same subject, and found water to have a 
maximum at 38°*804. The cause of differences so great must 
be determined by further investigation,— the thermometers are 
* Kong. Vet. Handlingar. 
f Poggendovf’s Annalen , xxi. p. 7-5. 
% Neues Physicalisches Wbrterbuch , iv. p. M9, 
