1813.] Definite Proportions in Chemical Comlinatio7is. 169 



Number of Weight of an 



atoms. integrant particle. 



141. Hydrate of alumina . .1 a + 1 w 4*632 « 



142. Hydrate of glucina . .1 g + 1 w 4.732 h 



143. Hydrate of yttria ...Ay + 8 w 1 1*796 i 



144. Hydrate of zirconia . A z + 1 iv 6.788 k 



145. Hydrate of silica ... .1 si + 1 w 5.198 ■ 



146. Hydro - sulphuric| m 



acid, or acid ol 1*85 J 



147. 2d hydrate of sul- 





phuric acid, or acid j> I s + 2 w 7*264 * 



of 1*780 

 148. 3d hydrate of sul-" 



phuric acid, or acid of J> 1 s + 3 w 8*396 



- 1-65 



149. Hydro-nitric acid,\ 

 or acid of 1-620 J 



2n+l w 8-888 



25 water, which agrees nearly with the number in the table. It 

 would not be surprising if a hydrate of magnesia existed con- 

 sisting of an atom of magnesia united with an atom of water, 

 but incapable of being dried without losing one-half of its water. 

 Wavellite may be considered as a native hydrate of alumina. 

 If it be composed of 74 alumina and 26 water, it must consist 

 of an atom of alumina + an atom of water. Alumina preci* 

 pitated from a solution, and dried at 60°, would appear, from 

 Saussnre's experiments, to be composed of 1 atom of alumina 

 and 4 atoms of water. 



h Stated merely from analogy, without any direct experiment. 



1 From the experiments of Klaproth, it appears that yttria 

 precipitated from acids, and dried, is composed 69 yttria + 31 

 water. Hence the number in the table. 



k According to Davy, zirconia, when in the state of a hydrate, 

 contains more than -£th of its weight of water. Hence the 

 number in the table must represent its composition. 



1 We have no direct analysis, of the hydrate of silica: but the 

 earth is known to absorb about |th of its weight of water. Hence 

 it must be a compound of 1 atom silica and 1 atom water. 



m This is the strongest possible sulphuric acid. It is composed 

 of 100 real acid + 22-64 water. 



n This is the acid which freezes at the highest temperature of 

 all, about 42 1 " Fahrenheit. It is that on which Mr. Keirmade 

 hi;> experiments. It is composed, as Dalton has shown, of 100 

 real acid -f- 4528 water. Hence its composition is as stated in 

 the table. 



This and the three following hydrates have been ascertained 



