216 A Tribute to the Memory of 
This fact suggested to him an eligible method 
of preserving water at sea ;* but as lime water 
is unfit for almost every culinary purpose, 
some simple and practicable method was re- 
quired of separating that earth from the water, 
before being applied to use. This, he ascer- 
tained, might beaccomplished at little expence 
by carbonic acid, the gas from a pound of 
chalk and 12 ounces of oil of vitriol being 
found sufficient for the decomposition of 120 
gallons of lime water.t ‘The only difficulty 
was in the mode of applying the gas on a large 
seale; but this was overcome by the contri- 
vance of an apparatus, which Mr. Henry des- 
cribed in a pamphlet dedicated to the Lords of 
the Admiralty. ‘The proposal, in conse- 
quence of the zealous personal exertions of 
Mr. Wedgewood, who was then in London, 
met with due attention from the Commissi- 
* Dr; Alston of Edinburgh appears, however, to have 
been the first who proposed impregnation with lime, as a 
mean of preventing the putrefaction of water; and to pre- 
cipitate the lime, he suggested the use of carbonate of mag- 
nesia. 
+ The water, however, for which these proportions were 
sufficient, could not have been completely charged with 
lime, for fully saturated lime-water would have required for 
decomposition nearly three times that quantity of chalk 
and oil of vitriol. 
