VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 45Q 



greater number of bright yellow spots, some of which were even much darker in 

 colour, and approaching to brown. A change had now evidently taken place, 

 which change increased on every repetition of the process; I therefore judged I 

 might follow this direction with confidence. But, with a view to use the greatest 

 accuracy and precaution in my proceedings and observations, I resolved to begin 

 my work over again. First, I procured some ounces of sedative salt, which had 

 been obtained from borax by means of vitriolic acid; and then prepared 2 quarts 

 of the above-mentioned oxygenated muriatic acid, by distilling 3 parts of muriatic 

 acid with 1 part of the purest manganese, in the usual manner; this I preserved 

 in a cool dark place. Thus, the substances used in the following experiments, 

 were always of the same nature. 



Exper. 5. I poured 3 oz. of the oxygenated muriatic acid on 4- oz. of the seda- 

 tive salt, in a white glass tubulated retort. I used such a retort, that, in fre- 

 quently pouring back the distilled fluid, I might not have to lute afresh the several 

 vessels, after every distillatory digestion. For the same reason also, I chose a tubu- 

 lated receiver, the tube of which gradually terminated in a point, in shape of a 

 funnel. This tube passed into a phial, placed in such a manner that all the fluid 

 passing into the receiver dropped immediately into the phial, the joinings of which 

 were closed with bladder. To close the tube of the retort, I did not think it right 

 to use a waxed cork, though it closes very tight, because it might be corroded; 

 and also because the vapours, dropping from the cork, might carry some fat and 

 oily matter back into the retort. For the same reason, I would not use any greasy 

 lute; but closed the joints of the glass stopper, which fitted remarkably close, 

 with a ring of fine sealing-wax, closely pressed on it, but which could easily be 

 disengaged, after my work was done, while the retort was still warm : and as I was 

 even afraid of an oily lute about the joints of the receiver, I closed them up with 

 a ring of very fine white clay, which I fitted to them as exactly as possible, by 

 pressure; letting it stand several days to dry, and then carefully filling up all the 

 cracks. Having made this previous arrangement, and put the above-mentioned 

 ingredients together, I suffered them to remain cold for 24 hours; at the end of 

 which, the salt was not entirely dissolved, but, on the application of heat, the 

 whole became a clear fluid.* The degree of heat in the sand was from 180° to 

 240°, by which the fluid evaporated very slowly. During this operation there 

 ascended, or rather crept up the sides of the retort, a considerable quantity of 

 salt, in very loose flowers, rising pretty high above the fluid, increasing by de- 

 grees, and chiefly occupying that half of the retort which received a greater degree 



# This appeared to me so striking, that I endeavoured to obtain a confirmation of it. I made a 

 similar mixture, in the same proportions, which was not dissolved so long as it remained cold j but was 

 dissolved by heat. When the solution cooled, a small part of the salt, and a larger as the cold in- 

 creased, precipitated, which was dissolved again by a fresh application of heat. But with the degree of 

 heat I employed, no more than 1 part of salt would dissolve in 6 parts of the acid.— Orig. 



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