376 Test for Platinum. 
and two feet above low tide, and fifty-six above the highest 
ground in the city ; is thence conveyed in the iron pipes 
described in our last Number, (page 173,) the whole ex- 
tent of which is now thirty-five thousand two hundred and 
five feet, “and in no instance has a leak been discovered.” 
The greater part of the pipes now laid are of American 
manufacture, none ever having been imported except as 
samples. 
The system obviously admits of indefinite extension. 
The committee justly remark that “the uses and importance 
of this water, it is impossible sufficiently to value. The 
additional cleanliness of the city, (which with the suburbs 
contains between 120,000 and 130,000 people,) the supply 
of the neighboring districts for culinary purposes, as well 
as for purposes of refreshment—the great advantage in case 
of fire—the ornament of fountains in the public squares so 
wisely provided by our great founder—the benefit to man- 
ufactures, and the establishment of water power in the city 
for various purposes, may be named among the advantages 
of this new work; but above all we are to place its effect 
upon the health of a great and growing community, which 
of itself would justify a much greater expenditure.””—Ed. 
13. Test for Platinum. 
In the course of various trials, with hydriodic acid, upon 
metallic soluiions, we were recently much impressed with 
its remarkable effect upon the muriate of platinum. If 
dropped into a solution of this salt, even when extremely 
dilute, it produces, almost immediately, (and immediately 
if the solution be of only moderate strength) a deep wine 
red, or reddish brown colour; by standing a few minutes, 
it grows much more intense, and becomes very striking, af- 
_ ter the lapse of ten minutes. It much resembles the effect 
of the recent muriate of tin, but is a more delicate test than 
that, as it produces decided results where that gives but a 
faint change of colour. By standing a day or two, the so- 
lution becomes covered on the top, and on the sides of the 
vessel, with a film of perfectly metallic platinum. From 
this circumstance, it appears that the test operates by redu- 
cing the solution to the metallic state. Perhaps this effect 
was favoured by the manner in which the hydriodic acid 
