bicarbonate—­acid calcium phosphate, calcium superphosphate and calcium sulphate.  Common baking powders often consist of the same ingredients, and sometimes also of magnesia and alum.  These are often made and sold by ignorant men, whose sole object is to make money.  Calcium superphosphate and acid calcium phosphate very frequently contain arsenic, and as the cheap commercial qualities are often used there is danger in this direction.  A good formula for baking powder is, tartaric acid 8 ozs., sodium bicarbonate 9 ozs., rice flour 10 to 20 ozs.  The last is added to baking powders to improve the keeping quality and to add bulk.  The ingredients must be first carefully dried, the sodium bicarbonate at not too high a temperature or it decomposes, and then thoroughly mixed; this must be preserved in well closed and dry bottles.  Another formula, which is slow rising and well adapted for pastry, is sodium bicarbonate 4 ozs., cream of tartar 9 ozs., rice flour about 14 ozs.  Custard powders consist of starch, colouring and flavouring.  Egg powders are similar to baking powders but contain yellow colouring.  Little objection can be taken to them if they are coloured with saffron; turmeric would do if it were not that it gives a slightly unpleasant taste.  Artificial colouring matters or coal tar derivatives are much used, several of these are distinctly poisonous.

Drinks.—­It is better not to drink during eating, or insalivation may be interfered with; a drink is better taken at the end of a meal.  The practice of washing down food with hot tea is bad.  The refreshing nature of a cup of hot tea, coffee, or cocoa is to a very great extent due to the warmth of the water.  The benefit is felt at once, before the alkaloid can enter the blood stream and stimulate the nerve centres.  Hot water, not too hot to cause congestion of the mucous membrane, is one of the best drinks.  When the purity of the water supply is doubtful, there is advantage in first bringing it to the boil, as pathogenic bacteria are destroyed.  Some find it beneficial to drink a cup of hot water the first thing in the morning; this cleanses the stomach from any accumulation of mucus.

If fruit, succulent vegetables, or cooked food, containing much water be freely used, and there be little perspiration, it is possible to do without drinking; but there is danger of taking insufficient water to hold freely in solution the waste products excreted by the body.

Aerated drinks, except a very few of the best, and non-alcoholic beers and wines, are generally unwholesome, from their containing preservatives, foaming powders, artificial flavourings, &c.