Returning to the water mattresses, I will show in figures, in the manufacturer’s price in 1850, and the manufacturer’s charge in May, 1856, (and it must be less at this moment,) and the uniform retail price, and to this latter I invite the special attention of your readers, and ask them carefully to note the _retailer’s profit_ on each, and decide the advantage to be derived from purchasing of the manufacturer. I have no personal interest in any of them. I will show also their usual sizes, and their weight, as they are all sold by the manufacturers, on this basis. I trust this may stir up increased demand for so useful and necessary an article for the alleviation of human suffering, the use of which the _immense retail profits have hitherto prohibited_ among the middle and humbler classes. The formula for water mattresses and cushions—(India-rubber) is:— s. d. 1 lb. Fara Gum (in sheet,) 2 0 (Present cost, 1s. 7d., per lb.) 6 oz. Oxide Zinc, 0 1½ 1 oz. Pure Sulphur, (common equally good,) 0 1½ Mill costs, 3 —— —— 2 5 Or 1s. 7d. per lb. Say of the above compound, 1 0 Making waste, 0 ⅓ Grinding, running, cleaning and vulcanizing, 0 6 Add 36⅓ mill profit, or 0 10 is 3 2 per lb. This is the price per pound the weight should be estimated at. The mattresses vary in size from 8 + 14 inches to 48 + 72—some with cells—some without cells. The _retail profits_ on these goods, over the manufacturer’s prices, in 1856, ranged from 13s. 6d. to £7, 6s.—according to the size of the mattress. Or in American currency, from about $3.00 to $36.00 profit on single mattresses. Should so serviceable an article be thus clogged and fettered by such immoderate charges by the retail shop-keepers? It may probably be a guide to some of our readers to state, the best size pillow is 17 + 22, and that the celled mattresses 27 + 30, and 30 + 40, are found most useful, and of adequate length to support the trunk of invalids, and admit the other portion of the body to rest upon the usual feather bed, and thus steady a weak patient; as a full length mattress of elastic gum, 33 + 72 is beyond the safe control of such invalids. The retailer, for obvious reasons, recommends the larger mattresses, and which are _not_ returnable, _even if the patient dies before they reach him_. CHAPTER VI. VALUABLE RECIPES, ETC. PURIFYING GUTTA-PERCHA.