A New and Curious variety of Combustion. 387 
The colour thus prepared, possesses a bluish shade; but 
the arts often call for a deeper shade, somewhat yellowisb, 
but of the same beauty and elegance. T'o effectthis change 
it is only necessary to dissolve a pound of common potash, 
in a sufficient quantity of water, and add to it ten’ pounds 
of the colour prepared as above, and warm the whole over a 
moderate fire. The mass soon deepens and acquires the 
requisite shade. Iftoo long boiled, the colour approaches 
to Scheele’s green, but always surpasses it in beauty and 
splendour. ‘The alcaline fluid which remains may be used 
in the preparation of Scheele’s green. 
covered in it, various earthy muriates, and a little oxide of 
iron. At length Angelini, an Apothecary at Voghera, by 
employing starch asa reagent, obtained the blue colour 
which indicates Iodine, and he succeeded in presence of Dr. 
Ricotti and Luc. Barenghi, in extracting a certain quantity 
of this substance bythe process which is followed in procur- 
ing it from the mother waters of salt petre. 
It is remarkable that for a long time, the mineral waters 
of Sales have been successfully employed in scrophulous 
affections, and especially in the dispersion of Goitres.” 
24,.—A new and curious variety of combustion.—Doberei- 
ner, professor at the university 0 Jenaa, has discovered 
that Platina, in a spongiform state, occasions, at common 
temperatures, the combination of oxygen and hydrogen, and 
that so much heat is developed from its action as to render 
the metal incandescent. 
placed in a stream of hydrogen gas, at the distance from the 
orifice in which it mingles with the atmospheric air. In 
