6 REPORT— 1847 . 
The accuracy of formula (2.) is therefore to the accuracy of formula 1 1 $ 
1:2-4. 
That the calculated values of the specific pmvitics according to my fonnuk 
do not differ much from the truth, or that the differcuces between the calcu¬ 
lated and observed values are within tho iiniit>i of the error* of olMervotioos. 
is plainly shown by a comparison between the resulu of the oaperiraents of 
TJre and Parkes, which exporinieiits seem to have bt*en executed with almost 
the same accuracy. I have calculated both series of experiments hr the 
me^od of least squares according to the formula log < = a T, from P = 0 
r* signifies the quantity of the first hydrate of sulphuric 
acjd (bO, + 11^0) which one part of the mixture contains. 
larkess ex^riineiits’* gives from thirty-eight observations tho most pro¬ 
bable value of <10 r 
a = 0‘282437 + 0-000318, 
^ ~ 0*00037; and Urt*'s cxiwriments give (Vom thirty 
« = 0-285432 ± 0-000236, 
•with a mean error = O-GOOS-t. 
a sneciflt!ll'^ -T'l mixture = P, had 
as both ^ ^ specific gravity of I'8485, and 
60° Falir mi#» • cxecuterl at tho saim* temperature, 
to Ure’s. This is tv-*!! "fi '^^hld bo somewhat greater than according 
is about 0-fiS ^ for the higher degrees of coucentration, 
at dm siLcifl^' acid the obovo values of« 
fhe differcricp 'lt^’IIL^ •» according to 
to Ure’s. 
until P 
UrT gravity aocor<li„g y 
quently tlirec 0-0025, cohse- 
formerly found. It Boemt tl .'*^r P'‘®’^ablo error of a single observation 
or perhaps both, are affected'^ “* 
b «« urea and Fmkess experiments within the gi 
a = O-OBJ.TQ'r -L rv-nr.^,.. . 
given limits are 
eciuivaJent of water raubhvdrnfl?'® t’OuiviUcnts of acid wim uu. 
two and three equivalents S”** ‘•O* ^cid with one, 
believed that there is sufficient renimr,^?”''^ chemists however have lately 
combination of one oquivalent of <lrv-I .t''®‘^PP°*c that there also exists a 
As now 100 part, ^ six equivalents of water. 
g + .a,co„.ainasj:e8pa.^ofSO, 
° - ipecac gravity „f the.. hyd..t« at G0» Faitr. is’as :- 
Sl’ccific gravity of According to 
SO^+iaq .. j.S'o- 
S03+3aq ;. 1-7639 
SOj + eaq ■■■■ ^*6394 
. 1*4010 1 ‘ 4,052 
* Chemical Essays. vol.i.p. 504. 
