424 Ohservalions respecling 



ratory, each weighing at least two hundred grains, were separately 

 i»ubmitted to the action of a sufficient quantity of diluted muria- 

 tic acid. The undissolved residuum, which amounted in no 

 instance to as much as four parts in a hundred, consisted of a 

 yellowish brown ochry clay, mixed with a few particles of white 

 sand, and small laminar fragments of a dirty-white colour, very 

 much resembling portions of the siliceous incrustation of the 

 Geyser s})ring. Small flocculcnt shreds slowly subsided in the 

 muriatic solution, derived probably from the membranous part 

 of the shelly matter of the limestone ; for this insoluble resi- 

 duum, when thrown into red-hot nitre, slightly deflagrated, and 

 gave out an odour resembling burnt bones : and as this residuum 

 had been collected without the use of a filter, the inflammable 

 matter could not well have been derived from any other source 

 than the stone itself. 



The muriatic solution contained a small proportion of iron, 

 and gave a very slight trace of magnesia. So that the compo- 

 sition of the stone may be thus stated : 



Carbonate of lime 96 



Oxide of iron, sand, ochry clay, and animal membrane . . 4 



100 



In offering the following imperfect analysis of the saltpetre 

 produced in the situations above alluded to, it is necessary to 

 state, that the quantities on which I have hitherto had it in my 

 power to operate have been very small. 



Some preliminary experiments made on a solution of saltpetre 

 which had been formed during the summer, gave the following 

 results. 



The solution contained no disengaged acid or alkali, and 

 upon the addition of oxalate of ammonia afforded the slightest 

 possible evidence of the presence of lime. It contained minute 

 portions of sidphuric and muriatic acid. A portion of it being 

 evaporated left a mass of crystals which, in their form, as in 

 all their other characters, exhibited the properties of nitrate of 

 potash. 



As it is usually stated by writers who speak of the subject, 

 that nitrate of lime is a principal constituent part of saltpetre 

 iormed by a natural process, I was much surprised by the very 

 slight trace of lime evident in the present instance ; though I 

 had felt assured previously that but little would be found in the 

 natural saltpetre which I have had an opportunity of examining; 

 having never observed in it any tendency towards deliquescence. 

 Having had frequent occasion to suppose that carbonate of lime 

 IS much more readily soluble in water than is commonly be- 

 lieved, and having never been able to detach the saline efflores- 

 cence 



