428 Transactions.— Chemistry. 
alkaline taste of soda-water, and has evidently built up, by its continuous 
depositions of the caleareous matter which it holds in solution, the whole of 
the white-erusted mound which surrounds the pool. 
“It may assist the imagination of the reader if he fancy a painter's 
palette, magnified to a diameter of fifty feet and placed on a low piece of 
New Zealand swamp and fern. The palette will represent the white mound 
formed by the calcareous incrustation, the thumb-hole, the bubbling spring. 
A wavy line drawn from the thumb-hole to the further extremity of the 
palette is the gutter by which the overflow escapes. 
‘ The deposit from the water is of two distinct kinds—the principal 
calcareous, and forming the bulk of the surrounding incrustation ; the other 
is soluble in water, has a caustie taste, and is found only during dry 
weather as a recent white efflorescence caused by exposure to the air, or as 
little starry groups of crystals in the water of the gutter (soda ?). The 
water is highly charged with carbonic acid gas—as much as five ounces by 
measure of this gas having been obtained from a soda-water bottle full of 
the water. That both water and carbonic acid gas (otherwise ‘foul air' 
or ‘ choke-damp ’) exist deep in the earth’s crust, is a fact well-known to 
every miner on the Thames. Deeper still than our mines have penetrated, 
what water there is must be under a great pressure, and thus rendered 
capable of absorbing a very large quantity of the gas. When thus super- 
charged with gas, it has the faculty of dissolving carbonate of lime in 
considerable quantity, and if it comes in contact with that substance under- 
ground will rapidly take it into solution. Suppose now the water, charged 
to excess with carbonic acid gas, and thereby holding carbonate of lime in 
solution, to force its way to the surface of the ground: The pressure is 
taken off; the gas escapes bubbling at the spring; and since the lime can no 
longer be held dissolved, it deposits itself wherever the decarbonized water 
runs from its fountain. Such a deposit is formed in New Zealand around 
many a less fascinating spring than that of Puriri, and we have found at 
such places mossy and other incrustations which rival the similarly grown 
travertine of Europe. Three other little bubbling springs were found in 
the immediate vicinity, all very small, and not one having any zone of 
incrustation. 
** Until a proper chemical analysis shall have been made, it is impossible 
to form an opinion of the value of this spring as a medicinal agent. That 
its mineral, gaseous, and other constituents possess some valuable proper- 
ties, I should think there can be little doubt ; and when these are better 
known it is possible that the medical men of the Thames and elsewhere 
may be not unwilling to recommend its use to their patients in certain 
: : | diseases for which it may be found beneficial." 
