830 Description of a Hydrometer. 
From Mr. London’s statement at a meeting of the committee, 
it appears that the brine ought always to contain a redundancy 
of salt; in such case there is not the least danger of the fish 
putrefying or growing rancid, as the extra lumps of solid salt in 
the brine immediately act upon any watery or other liquors 
which proceed from the fish when inclosed in the cask. That 
the same process will also answer perfectly well for preserving 
beef or any animal food for sea store. 
Certificate. 
Mr. London cured by his new process under my immediate in- 
spection upwards of 25,000 mackerel at Ramsgate, in Kent, 
during the last season. 
Joun Cutter, Licensed Fish Curer, 
Sept. 28, 18149 at Ramsgate, Kent. 
ee 
Reference to the Engraving of Mr. Lonpon’s Hydrometer, 
Plate IV. fig. 3. | 
This instrument consists of a glass bottle, with a ground-glass 
stopper, to be filled with brine made from a solution of solid salt 
in water; within it are three glass bubbles, a,l,c, of different 
specific gravities, so graduated that, supposing, the temperature 
of the air to be at sixty degrees of Fahrenheit’s thermometer, 
and only one bubble-floats on the surface, as shown in the en- 
graving at a, it indicates the specific gravity of the brine to be 
1,155, containing about 20 parts salt, and 80 of water, which is | 
insufficient to cure animal matters with certainty by immersion 
in it. 
When the second bubble, c, floats, it indicates the specific 
gravity of the brine to be 1,180, or about 24 parts salt, and 76 
parts water, which may be used for the purpose of immersion. 
But when the three bubbles, a, 2, c, float, they indicate the 
specific gravity to be 1,106, or about 28 salt, and 72 water. 
This brine will fully answer the purpose in the hottest weather 
in most climates, provided the rules be attended to which I had — 
the honour to send to the Society last year, and the meat or 
fish always completely covered with the brine. “J 
Puiturs LONDON. — 
