The quantity of real alkali contained in the commercial alkalies (common soda, soda ash, potashes, pearlash, salt of tartar, etc.) is ascertained by the quantity of an acid solution of known strength required to neutralize it. For this purpose a tube, termed an Alkalimeter, is used, which will hold 1000 grains of water. The tube may be three fourths of an inch internal diameter, and 9 1/2 inches in length; or five-eighths of an inch diameter, and 14 inches in height; and should be graduated into 100 equal divisions numbered from the top downwards. The quantity of test acid used is then at once seen. This consists of sulphuric acid diluted with water, so that each measure (10 grains) is equivalent to one grain of pure soda. To use it, dissolve 100 grains of the impure soda in 3 oz. of hot water, filter, and wash the filter. Then add to the solution the test acid until the litmus or cabbage paper ceases to show an alkaline reaction. The same acid will serve for potash, if the number be multiplied by 3 and divided by 4. - Parnell. There are several other methods of performing the process given in the larger manuals. Allots and Amalgams. A few only of these metallic compounds require notice here: - Fusible Metal. 1. Tin 8 parts, lead 4, bismuth 3; melt together, removing the scum. Used as a metal-bath.

2. Daecet's for the same purpose: Bismuth 8 parts, lead 5, tin 3.

3. Lead 3 parts, tin 2, bismuth 5. This melts at 197° Fahrenheit.

4. For anatomical injections: Melt together with a gentle heat 174 parts of tin, 312 of lead, 514 of bismuth, with a little charcoal: remove from the fire, and add 100 parts of mercury, previously heated. It is fluid at 173°; solid at 140° Fahrenheit.