[ 47° 3

II. Platina with the Marine acid.

1. Weak and strong spirits of salt being digested se-parately with one third their weight of platina, in agentle heat, for several hours, the liquors remained un-coloured, and the platina unaltered. The heat was after-wards increased, and the liquors kept strongly boiling tillthey had totally exhaled, without making any sensiblechange in the platina.

2. When common salt is strongly heated, in mixturewith certain vitriolic substances, its acid, forced out bythe vitriolic acid, and resolved into fumes by the heat,corrodes some metallic bodies, on which, in its liquidstate, it has no action. Two pajts of decrepitated or driedsea salt were therefore mixed with three parts of greenvitriol calcined to redness; three ounces of the mixturepressed smooth into a cementing pot; one ounce ofplatina spread evenly upon the surface, and some moreof the mixture over it; the vessel closely covered andluted, and kept in a moderate red heat for twelve hours.On examining it when grown cold, the saline mixture wasfound to have melted, and formed a smooth uniform mass..The platina, which had funk to the bottom, being se-parated from the mixture by washing, appeared to havesuffered no change, though its weight was a little diminished,

3. The experiment was repeated with a less fusiblemixture, called the regal cement, composed of one part ofcommon salt, one of colcothar, or vitriol strongly calcined,,and four of powdered red bricks. An ounce of platina,surrounded as above with six ounces of this composition,and cemented in a close vessel, with a red heat, for twentyhours, suffered no material change, though there was; asbefore, some deficiency in the weight. Many of thegrains were discoloured; whereas, in the foregoing ex-periment