i6o Vfeful Applications of Oxymurlate of Pot a Jh. 



bubbles of air are jufl beginning to rife in the faline liquor in the operation of making it: or 

 if it is faturated above that point, a little more alkali may be added, or the phial in which it 

 is preicTved, may be left open until the air-bubbles ceafe to rife. 



I have obferved in all the experiments made with this fait, that it produces the fame efFedt 

 upon moft colours as expofure to the air and fun, with this difference only, that its operation 

 is much more rapid and complete : therefore, I have accounted for its efFsfts, by fuppofing 

 that when a proper quantity of the fait was added, the colouring particles attraded as much of 

 oxygen from the fait, as wras fufficient to give them their greateft degree of intenfity and 

 brifThtnefs ; but when too much of the fait was added, fo much oxygen united with the 

 colouring particles as to oxydate them completely, and deftroy their colour : probably the 

 indigo (the colour of which is more or lefs difcharged by all proportions of this faline folution)' 

 is fufficiciitly oxygenated in the operation of making it. 



As in all the experiments tried upon colours, the oxygenated muriate of carbonated potafh 

 produced a better efFecft than the oxygenated muriate of potafli ; it is probable that the 

 carbon, or carbonic acid, a£ls a very important part. What renders this more probable is, that 

 charcoal, when ufed for purifying any fubftance, but particularly ardent fpirits, extradl of galls, 

 or water become putrid, by (landing too long in glafles, with flowers, &c. if left on the filter, 

 expofed to the air and fun, and not fufFered to dry too quickly, afTumes a variety of beautiful 

 colours, principally blue, yellow, and purple. When the colour, therefore, is improved by the 

 oxymuriate of carbonated pot-afli, both the oxygen aad carbon may unite with the colouring 

 particles, and produce a joint efFefl:. 



The oxymuriate of carbonated potafh, when not ufed in excefs, precipitates many of the- 

 metals from their folvents, with a great deal of colour, and, in many cafes, may be advan- 

 tageoufly ufed to deteft the prefence of a metallic oxyde diffolved in water. 



Soap is improved by mixing it with a fmall proportion of this faline folution ; common foap,. 

 if well mixed with it in a mortar till it becomes white, anfwers better for wafhing the hands, 

 or {having, than any of the kinds of foap moft ftrongly recommended for thefe purpofes. 



All the fiit and exprefTed oils are rendered as white as milk, and partly foluble in water, by 

 mixing them with this faline folution; and they may be reflored to their former ftate, by a 

 fmall addition of any of the mineral acids, excepting a fmall quantity of a mucilaginous fub- 

 ftance, which remains for a while fufpended in the water, and at laft colledts upon its furface r 

 common whale-oil treated in this way, lofes much of its ofFenfive fmell, and becomes better. 



Thefe are a few of the obfervations I have lately made upon the effefls produced by oxyge-' 

 nated muriate of carbonated potafh. Though I have not had an opportunity of making fo many 

 experiments, or of confidering their refults with all that attention which they feem to deferve, 

 yet as many of them are entirely new to me, and promife to be ufeful to fociety, I have pre- 

 fumed to lay them before the public, even in their prefcnt imperfedt ftate, through the medium 

 ©f your very excellent publication. 



Belhelvifj hy Abtrdeen^ June 2, 1799. A. I. F. 



On 



