SECONDARY STANDARDS. 
937 
In air for vvhicli log A=7‘07832— 10, displaces 2‘2211grs., and 91— r4gr. of 
platinum displaces 0*8998 1 gr. Therefore IBv+r3683 gr. 91, But 9i:0:IL-l-T3673 gr. 
Hence, when weighed in air of the above-mentioned density, iBv appears to beO'OOlOgr. 
lighter than 
Troy Ounce fVeights. 
A series of troy ounce weights from 500 ounces down to 0*001 ounce, of gun-metai 
protected by electro-gilding, was constructed by Messrs. Ladd and Streathpield for 
the use of the Exchequer. Each weight will be designated by the number expressing 
its approximate value in troy ounces, with a letter to distinguish it from other 
weights of nearly the same value. For the weights marked s, t, z log A = 0*92768 ; 
for those marked m, n log A=0*92501. T denotes the platinum troy pound ; U the 
lost standard troy pound, or 12 troy ounces. The comparisons of different combina- 
tions of these weights with T, and with one another, gave the following results: — 
No. of Comp. 
S'"* 
t. 
b. 
28 
An + At-\-2n + 2t bib T— 0*02166 
18*6 
754*6 
24 
\Qn + ^{2n + 2t) biT-|- 0*00078 
19*14 
739*47 
20 
lO^ + ls-hla; £bT-F0*01370 
17*13 
751*52 
24 
56--|-4it+ls-t-2if biT-l- 0*00228 
17*78 
760*1 
48 
10s+ls-(-lx £ 1 :T+ 0*00774 
17*9 
755*68 
32 
\Qm + 2m £i:T + 0*00060 
17*66 
763*62 
32 
4s + 4»j + 2s + 2rrtbiT — 0*0031 1 
16*5 
763*44 
In air for which log A = 
7*07832-10, 
gr. 
An-\-Al+2n + 2t biT-0-02133 
\Qn + \{2n + ^t) £bT-h0*00253 
10«+ls-)-lir £bT + 0-01387 
bs + U+Xs + ’Zt £bT + 0-00688 
10s+ls+l:c £}:T + 0-00925 
10?w + 2>w £bT-|-0*00781 
+ + £bT-l- 0*00639 
T ^U-0*00745 
Since these weights, the densities of which do not differ much from that of the lost 
standard U, are intended for use as commercial weights without applying any correc- 
►r the weight of the 
air displaced, = may be substituted for 
allies in 
terms of U 
in air for which log A=7'07832— 10. 
oz. gr. 
4n + 4if4-2w-|-2/! =12 — 0*02878 
1 
\t)n + \(2n-{-2t) =12 — 0*00492 
2 
lOf-l-ls+la; =12-1-0*00642 
3 
5s+4^-f ls-t-2^ =12-0*00057 
4 
lOs+ls-t-la: =12-1-0*00180 
5 
10m-|-2/» =12 + 0*00036 
6 
4s + 4/?i + 2s + 2;n =12 — 0*00106 
7 
No. of Comp. 
gr- 
10 
At 
= 2f + 2w 
+ 0*01685 
8 
10 
An 
= 2#+2w 
— 0*00090 
9 
26 
2t 
= 2w 
+ 0*01121 
10 
24 
10« 
= 5s+5m 
+ 0*00188 
11 
16 
5s 
+ 0*00041 
12 
10 
Is 
= Im 
+ 0*00046 
13 
