The disease is characterized by the appearance of a mycelium forming white or greyish-white patches on the young leaves; this spreads quickly and attacks the older leaves and branches, and ultimately reaches the grapes.
Caesium hydroxide, Cs(OH) 2, obtained by the decomposition of the sulphate with baryta water,is a greyish-white deliquescent solid,which melts at a red heat and absorbs carbon dioxide rapidly.
This under-coat, or pushm, which is of a uniform greyish-white tint, whatever the colour of the hair may be, is beautifully soft and silky, and of a fluffy description resembling down.
From the heating of native calcium sulphate and carbon is obtained calx sulphurata (U.S. and B.P.), or sulphurated lime, a greyish-white powder.
If the substance does not melt but changes colour, we may have present: zinc oxide - from white to yellow, becoming white on cooling; stannic oxide - white to yellowish brown, dirty white on cooling; lead oxide - from white or yellowish-red to brownish-red, yellow on cooling; bismuth oxide - from white or pale yellow to orange-yellow or reddish-brown, pale yellow on cooling; manganese oxide - from white or yellowish white to dark brown, remaining dark brown on cooling (if it changes on cooling to a bright reddishbrown, it indicates cadmium oxide); copper oxide - from bright blue or green to black; ferrous oxide - from greyish-white to black; ferric oxide - from brownish-red to black, brownish-red on cooling; potassium chromate - yellow to dark orange, fusing at a red heat.