[ 4H ]

rugineous matter, or the alcaline lixivium being less satu-rated with the substance which tinges dissolved iron blue,than those which Mr. Marggraf employed.

To obtain a saturated solution of this tinging substance,which cannot be expected to be done by calcining alcalinesalts with blood or other like matters, I digested somecommon Prussian blue both in solution of fixt alcaline salt,and in volatile spirit of sal ammoniac prepared with quick-lime. Both menstrua soon became yellow; and the ironybasis of the Prussian blue, thus freed from its colouringmatter, remained in a rusty form. To both tinctures Iadded some more Prussian blue, till they ceased to haveany action on it. The fixt alcali, along with the tingingsubstance, appeared to have taken up some of the iron;,for it struck a blue colour with good aquafortis, with theacid of sulphur, and with distilled vinegar, in which therewere no grounds to suspect any iron to be previously con-tained. The volatile tincture appeared free from iron, forin the same acid spirits it produced no change, though itinstantly turned them blue when a little iron was first dis-solved in them.

This saturated solution of the tinging substance was addedby degrees to solution of platina. The liquor turned atfirst to a deep blue, but on further additions, to a greenishyellow. The precipitate was of two kinds, yellowish atthe bottom, and blue on the top. The whole beingshaken together and set by till next day, a white matterappeared at the bottom, above this a yellow, and on thetop a more copious brownish grey. The liquor was of a«.deep gold colour.

IX. Solution of platina * with compoundsalts.

Solutions of alum, of sal mirabile, of vitriolated tar-tu, of the fusible salt of urine, made separately in water,.