S UL

SUL

( 374 )

red that fulphuric acid was compofed of 71parts fulphur to 29 parts oxygen. In this efti-mate however the proportion of fulphur ismanifellly exaggerated, for by the combuftionof fulphur in oxygen gas, a quantity of ful-phurous acid will be produced as well as offulphuric, the former of which contains amuch greater proportion of fulphur than thelatter.

•The feeond method is that by Berthollet , asfollows. Having afcertained that nitre and ful-phur in the proportion of four parts of theformer to one of the latter when heated in aretort, re-afted on each other quietly and with-out explofion, he mixed together 28S grs. ofnitre, and 72 grs. of fulphur, and heated themixture in a glafs retort till the emiflion ofnitrous gas entirely ceafed: during the proctfs,12 grs. of fulphur had fublimed unaltered, and.223 grs. of fulphat of potafli were producedby the combination of the alkaline bafe of thedecompofed nitre with the newly produced ful-phuric acid. Now according to Kirwan, ful-phat of potalh is compofed of 45.2 fulphuricacid, and 54.8 potafli, therefore out of the 228grs. of fulphat of potafh, 103 grs. were fulphuricacid, compofed of 72—12=60 grs. fulphur,and 43 grs. oxygen; hence 100 parts of ful-phuric acid confili of

58.2 Sulphur41.8 Oxygen

100.0

The third method, which has been followed■by Berthollet , Thenard, and Chenevix, andwhich appears upon the whole the belt, is todigefl: a given weight of fulphur in nitric acid,till it is completely difl'olved and acidified(which if performed with care may be effectedwithout the production of any fulphurousacid) then to add a folurion of nifrat or muriatof barytes as long as any precipitate takesplace, by which the whole of tire newly-formed fulphuric acid will combine with bary-tes into an infoluble fait; then to edulcorateand ignite the fulphated barytes, and from itsweicht to dedu£t that of the barytic bale; 'theremainder confequently will indicate theamount of fulphuric acid produced, from whichby iubtrafling the known weight of fulphur,we get by inference that of the oxygen. But.though this mode of proceeding is apparentlyunexceptionable, yet unfortunately the differ-ences in the quantity of fulphat of barytes pro-e Encydop. Method. Art. Acids Vitrialujuc.

duced, and in the eftimates of the componentparts of this earthy fait are fo prodigious as tothrow great uncertainty upon the fubjedt. Inthe experiments of Berthollet / 288 grains offulphur being digefled with nitric acid, 199 grs.remained undiflolved, therefore 89 grs. wereacidified; muriat of barytes being added therewas produced 948 grs. of fulphated barytes,which by ignition was reduced to 920 grains,therefore 100 grs. of fulphur would have af-forded 1033 h rs - 0; f fulphated barytes.

On the other hand, Mr. Chenevix 1 * acidified100 grs. of fulphur by digeftion in nitric acid,and by the fubfequent addition of nitrated ba-rytes obtained 694.gra.-of fulphated barytes.

Laftly, M. Thenard,' by operating in a fi-milar manner, obtained from 100 grs. of ful-phur 720 grs. of fulphated barytes.

The above differences in the refults of expe-riments made by men of acknowledged skill inchemical analyfis, are of themfelves fufiicientcaufes of uncertainty, but the difficulty of de-ciding will be much increafed when thefe vari-ations are further modified by the different es-timates of the component parts of fulphatedbarytes. According to Klaproth , Withering,and Black, this fait contains about 33.33 percent, of acid. According to Chenevix, it con-tains 23.5 of acid; and according to Thenard,25.18 of acid. (See Sulphat of Barytes.

Hence by compounding the above refults,the 1033 grs. of fulphated barytes, obtained byBerthollet , indicate the compofition of ful-phuric acid to be according to

• Klapr.

Thenard.

Chenev.

24.3

— 37-4 -

- 41.2 Sulphur

75-7

— 62.6 —

- 58.8 Oxygen

ICO.

IOO.

IOO.

The 694 grs. of fulphated barytes obtainedby Chenevix, from the acidification of 100 grs.of fulphur, indicate the compofition of ful-phuric acid to be according to

Klapr.

Thenard.

Chenev.

43.2

— 57-4 —

6 1.5 Sulphur

56.8

— 42.6 —

38.5 Oxygen

IOO.

IOO,

roo.

S'. 1 1 ■

«===3

■ .

And the^72o grs. of fulphated barytes, ob-tained by ihenard, indicate the compofition offulphuric acid to be according to

h Phil. Tranf. * An. xle Chim. xxxii. j>. 266,