§62 Dr. higgins on the Ufe of an Amalgam of Zinc. 
round; and that in this method of cleanfing the glafs 
cylinders, we avoid the inconvenience of removing the 
culhion, and the danger of fcratching the glafs, to both 
which we are expofed in the ufe of whiting and other 
cleanfing powders. 
I am, See. 
