. 
442 Introduction of Satmon 
England, and has been proved so to be by men of first- 
rate science before a committee of the House of Commons 
when deliberating on the water question for the supply of 
London ; and personally I have tested its purity. I am 
therefore convinced that by the time the vessel had left the 
equator, and had reached the cooler latitudes, the putres- 
cence was completely washed out of the spawn-tub by the 
regulated supply of new water taken from the store tanks to 
replenish as previously, and which retained its purity and 
soundness to Van Diemen’s Land. 
As regards the water in the spawn-tub appearing strongly 
to be impregnated with oxide of iron, I must say I have 
strong reasons to believe to the contrary; and I have much 
to regret that Mr. J. L. Buinett and Dr. Milligan did not 
test the residuum, as the water sent out to replenish the 
spawn-tub was taken from a spring of 55 degrees tempe- 
rature, rising from a depth of several hundred feet from the 
surface of the earth, and flowing out of the chalk hills of 
Surrey ; consequently little impurity could exist, save car- 
bonic acid and lime slightly in excess, which would only 
tend to keep the water in a purer state. 
I further conceive that the discoloration of the stones and 
gravel in the spawn-tub must haye been produced by car- 
bonate of lime of the water, through the evaporation caused 
by the great heat of the tropics. 
Being in doubt, therefore, on the subject, I exceedingly 
regret that these intelligent gentlemen overlooked this in- 
teresting test, or the examination of the tanks in which the 
store water had been conveyed, more especially as the tanks 
had been filled with Thames water many weeks previous to 
the refilling for the voyage, in order to season them, during 
which time no oxide had formed or oozed through the var- 
