i-8 Mr. Cavendish’s Account of 
It mud be obferved, that fmall fpicula of ice always came over 
along with the decanted liquor ; and to this, in all probability, 
the new-formed ice attached itfelf; for otherwife it is likely, 
that no ice would have been produced. 
The following table contains the (Length of the acids as 
determined before they were- fent to Hudfon’s Bay, and the 
quantity and {Length of the decanted and undecanted parts 
when they arrived at London, and the (Length of the whole 
mafs as computed from thence. For the fake of uniformity, I 
have exprefi'ed their {Lengths, like thofe of the nitrous acid, 
by the quantity of marble necefl'ary to faturate them, though 
I did not find their (Length by actually trying how much mar- 
ble they would diffolve ; as that method is too uncertain, on 
account of the felenite formed in the operation, and which in 
good meal ure defends the marble from the a&ion of the acid* 
The method I ufed was, to find the weight of the plumbum 
vitriolatum formed by the addition cf fugar of lead, and from 
thence to compute the flrength, on the fuppofition that a 
quantity of oil of vitriol, fufficient to produce ioo parts of 
plumbum vitriolatum, will diffolve 33 of marble as I found 
by experiment that fo much oil of vitriol would faturate as 
much fixed alkali as a quantity of nitrous acid fufficient to dif- 
folve 33 of marble. It may be obferved, that the quantity of 
alkali, necefiary to faturate a given quantity of acid, can hardly 
be determined with much accuracy, for which reafon the fore- 
going lefs dire« 5 l method was adopted ; efpecially as the precipi- 
tation of plumbum vitriolatum (hews the proportional {Lengths, 
which is the thing principally wanted, with as great accuracy 
as any method I know. 
N° 
3 
