XIII. Platina, Lead, and Acids.

Tiiin plates of lead put into solution of platina are sooncorroded, and white crystals form at the bottom with ablackista matter intermixed, the liquor continuing yellow:the crystals dissolve in water, leaving the blackish powder,which appears to be platina. Marggraf, from whom thisexperiment is taken, tried also solutions of lead, made bothin aquafortis and in distilled wine vinegar, and relates thaton mixing these solutions with solution of platina, no pre-cipitation ensued; a phenomenon not a little remarkable,as solutions of lead, made in either of the above menstrua,are in general precipitated by aqua regia or liquors contain-ing the marine acid. If there was no error or deceptionin these experiments, it might be concluded from them,that the marine acid has a greater affinity to platina thanit has to lead; but with me the event was otherwise. Asolution of lead in aquafortis, and a solution in distilledwater of crystallized saccharum saturni which I had pre-pared myself, being drops into separate portions of solutionof platina, the first drops produced no apparent change,but on continuing to add more of the lead solutions, bothmixtures grew turbid and milky, and deposited quicklyvery copious white precipitates, the liquors continuingyellow like diluted solutions of platina. I repeated theexperiment three or four times with disserent solutions ofplatina, and the appearances were always the fame.

XIV. Platina, Regulus of antimony, and Aqua regia.

Marggraf found, that a piece of pure regulus of an-timony, digested in solution of platina, was attacked by theacid. A good deal of white powder settled at the bottom,which was doubtless for the most part some of the reguluscorroded: the rest of the regulus was reduced into small

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