282 Mr. R. Phillips ona [Ocr. 
To 736 grains of this solution, water was added as long: as 
precipitation took place ; the precipitate was dried by exposure 
tothe air, and weighed 40 grains; 100 grains of the solution 
would, therefore, give 5:43 grains. I repeated this experiment 
with 1020 grains of the solution, which yielded 52-5 grains of 
precipitate dried as before; 100 would consequently have 
afforded 5:14 grains, giving a mean of 5:23 grains of subsul- 
phate of alumina from 100 grains of the solution. 
To determine the quantities of sulphuric acid and alumina 
which the precipitating sulphate of alumina contained, muriatic 
acid was added to 392 grains ; this acid was of course employed 
to prevent the action of the water ; nitrate of barytes was added, 
and 6]: grains of ignited sulphate of barytes were obtained, equi- 
valent to 15°56 per cent.; this experiment was repeated with 
205 grains of the solution, and 31:9 of ignited sulphate of 
barytes were procured, giving also 15°56 per cent. As 118 of 
sulphate of barytes are equivalent to 40 of sulphuric acid, 15°56 
will indicate 5°27, and consequently 100 grains of this solution 
contain 5°27 of sulphuric acid. 
To 633 grains of the same solution, with which a little muria- 
tic acid had been mixed, solution of carbonate of soda was: 
added, until it was slightly in excess. The precipitated alumina, 
after beg washed and ignited, weighed 36 grains; 100 grains 
of the solution would, therefore, have yielded 5°68 grains: this 
experiment was repeated with 625 grains of the solution, and 37 
of ignited alumina were obtained; 100 of the solution would, 
therefore, have afforded 5°92, giving a mean of 5:8 of alumina 
for 100 of the solution. From this, however, for reasons already 
stated, we must deduct 7°36 per cent. which reduces it to 5°38. 
It appears then that 100 grains of this solution contain 
Sulphinsieraetdindl. wij. tai duccsicin d datele rela 5:27 
init, | otters ces ek a 5:38 
According to Dr. Thomson, hydrogen being 1, an atom of 
sulphuric acid is 40, and of alumina 18 ; and as 5:27 : 5°38 :: 40 
740:83 the sulphate of alumina of this-solution would not appear 
to be reducible to a probable definite compound ; but I have 
already mentioned that a deposit was formed in it which appeared 
to be the same sulphate as. that held in solution, for water con- 
tinued to decompose the latter. 
The deposited sulphate, when dried by exposure to air, is in 
some places opaque, and in others transparent; and when in 
the latter condition, it has the appearance ofhorn. To ascertain 
its composition, I dissolved 50 grains of it in dilute’ muriatic 
acid, and added a solution of muriate of barytes ; 38°5 of ignited 
sulphate of barytes were obtained ; therefore, 100 grains would 
have given 77 grains, equivalent to 26:10 of sulphuric-acid:. To 
ascertain the proportion of alumina, 100 grains dissolved in dilute 
