ON PREPARING PHOSPHORUS BOTTLES. 105 



a circumstance that exclude* all galvanic influence: that 



it ceases, when this water has been deprived of air by boiV- a«long as the 



i i e . +u, 4. :* water contains 



ing, or by exposure to the vacuum ot an airpump : that it air; 



stops, when the air the water was capable of furnishing is 

 exhausted : that it recommences, when air is restored to the 

 water: that the presence of any neutral salt, as the sul- but not in wx- 

 phates, nitrates, muriates, in ever so small a quantity, as ^^uTS"' 

 for instance 0*002 of sulphate of lime, is sufficient to ob- salt. 

 struct this action : and that to this is owing the preservation 

 of lead without alteration in the water of the Seine, in 

 well-water, &c, whether in open or in covered vessels. 

 Hence this metal may be considered as one of the most ac- 

 curate tests of the purity of water, provided the water con- 

 tain no salt with excess of acid. 



With regard to the nature of the product of this action. The product 

 there is a manifest oxidation of the metal, but without any 

 decomposition of the water; different from that of iron, or 

 of zinc, which takes place in common water as well as in 

 distilled water, and even in that which is totally deprived 

 of air. It is not a simple oxide however: its lightness; its 

 ilocculent form; its bilvery lustre; the crystalline points 

 perceptible on the surface of the sediment; the state of 

 litharge of a golden yellow, which it assumes when heated ; . 

 the rapidity with which the approach of a hidrosulphuret 

 gives it the appearance of a gakena in shining scales; and 

 lastly the drops of water, which the heat of the sun extri- 

 cates from it after it has been long dried in the open air, 

 with the little effervescence it produces in acids ; lead the 

 author to suppose, that this product is of the nature- of a i s probably* 

 hydrate. hydrate. 



VI. 



Improved mode of preparing Phosphorus Bottles. In a 

 ' Letter from a Correspondent. 



MOULD Mr. Nicholson think the following observations 

 worthy a place in his valuable Journal, they perhaps may 

 tend to lessen a difficulty occasionally experienced by indi- 

 viduals, in the prosecution of a favourite study. 



It 



