2. Heavy carbonate of magnesia, 11⁄2 dr.; refined sugar, 1 oz.; essence of lemon, 5 or 6 drops; water, 8 fl. oz.; bottle as last, then add of citric acid (cryst.), 3 dr., and instantly cork, &c., as before. For a dose. It should be kept for at least 24 hours before being taken.
Lemonade, Lactic. Syn. Limonadum lacticum, L. Prep. (Magendie.) Lactic acid, 1 to 4 dr.; syrup, 2 oz.; water, 1 pint; mix. Recommended in dyspepsia, &c.
Lemonade, Milk. Syn. Limonadum lactis, L. Prep. Take of sugar, 1⁄2 lb.; water, 1 pint; dissolve, add the juice of 3 lemons; milk or whey, 1⁄2 pint; stir the whole together and strain through a hair sieve. Some persons add a glassful of sherry.
Lemonade, Min′eral. Syn. Limonade minerale, Fr. On the Continent this name is applied to various drinks consisting of water acidulated with the mineral acids and sweetened with sugar. Thus we have limonade chlorhydrique, nitrique, phosphorique, sulphurique, &c., all of which are used as cooling drinks in fevers, inflammations, skin diseases, &c.
Lemonade, Port′able. See Powders.
LEMONADE POWDERS. See Powders.
LEMONATED KALI. See Kali, Potassium (Citrate), &c.
LEN′ITIVES. In medicine, purgatives which act in a gentle manner, and have a soothing effect. See Laxatives.
LENS. In optics, a piece of glass or other transparent medium, having one or two curved surfaces, either convex or concave. A description of the different kinds of lenses belongs to a work on optics. It may, however, be useful to the chemical student to remark here that the Coddington and Stanhope lenses, which may now be bought at any of the opticians, neatly mounted and of great power, for a few shillings, will be found of the greatest service in examining minute crystals, precipitates, &c.; and for all ordinary purposes offer a cheap and efficient substitute for more complicated microscopes. An extemporaneous instrument, possessing considerable power, may be made by simply piercing a small circular hole in a slip of metal, and introducing into it a drop of water, which then assumes a spherical form on each side of the metal, while the latter is held in a horizontal position. The ingenious little TOY MICROSCOPES sold about the streets of London, under the form of a perforated pill-box, at one penny each, consist of such a lens made with Canada balsam instead of water, which has the property of hardening without losing its transparency after exposure for a few hours to the air. A still simpler substitute for a lens is a piece of blackened card-paper
with the smallest possible needle-hole pierced through it. Any very small object held in a strong light, and viewed through this hole at the distance of about an inch, will appear quite distinct, and from 10 to 12 times larger than its usual size. We have often found this little instrument of incalculable service in situations and under circumstances in which a more powerful or complicated apparatus was unattainable or could not be applied.