Page:The American Cyclopædia (1879) Volume X.djvu/94

 88 LACTIC ACID concerted into lactic acid. If a succeeding fermentation be allowed to take place, butyric acid is produced. The composition of lactic acid is expressed by the formula CsHeOs, and it has the same centesimal composition as sugar of milk. When concentrated in vacua over sulphuric acid, lactic acid is obtained in the form of a sirupy colorless fluid, of specific gravity T215 and very sour. At a temperature of 266 F. it yields water and becomes an an- hydrous solid (dilactic acid), which dissolves sparingly in water, but readily in alcohol and ether. Lactide is a crystalline substance^ of composition C 3 H 4 2, produced by subjecting the acid to a temperature of 482 ; it is now called lactic anhydride. In the animal econo- my lactic acid is thought to play an important part from its property of dissolving large quan- tities of freshly precipitated phosphate of lime ; and this has led to its prescription in medicine with the view of its removing phosphatic de- posits in the urine, as well as to hold in solu- tion phosphate of lime when given as a medi- cine. It has also been recommended in certain forms of dyspepsia. It has been proposed as a local application to dissolve the false mem- branes of croup, being applied in liquid form, or as a spray from an "atomizer;" but the success obtained with this treatment by other observers has not equalled that claimed by the original proposer. The acid may be conve- niently prepared by evaporating sour milk to one eighth its bulk, filtering, adding lime, again filtering, separating the crystals of lactate of lime which form, purifying these by redissolv- ing and recrystallizing, and finally decomposing the salt by means of oxalic acid and recovering the lactic acid by filtering. But it is best ob- tained by dissolving 8 parts of cane sugar in about 50 parts of water, and fermenting by 1 part caseine and 3 parts chalk, and decompo- sing the lime salt by sulphuric acid. The salts formed by this acid with bases are called lac- tates. The only important one is the lactate of iron, which is much employed in medicine as a stimulant and tonic. It is prepared by digesting lactic acid and iron filings at a gentle heat on a sand bath for five or six hours, and then allowing the liquor to boil. It is then filtered, concentrated, and allowed to cool and crystallize. The crystals are drained in a fun- nel, washed with alcohol, dried rapidly, and transferred to a bottle, which must be well stopped. Lactate of iron when pure is in white crystalline plates. It has an acid reac- tion, is soluble in 12 parts of boiling water, and the solution soon becomes yellow from the iron passing to a higher degree of oxidation. When sold in a powdered state, it is apt to be adul- terated ; for this reason it should be purchased in the crystals. The medicinal applications may be in the form of lozenges or sirup. In one of the Paris hospitals it has been intro- duced into bread, hence known as chalybeate bread, a grain of lactate of iron in each ounce, which does not injuriously affect the taste or LADD quality of the bread. This is given to patients suffering from chlorosis, and in other forms the medicine has proved beneficial in this dis- ease. It is observed that it decidedly increases the appetite. Sarcolactic acid is the variety which is obtained from the juice of flesh; paralactic acid also exists. LACTOMETER. See GALACTOMETEB. LACUSTRIANS. See LAKE DWELLINGS. LADAKII, or Middle Thibet, a state of central Asia, subject to Cashmere, bounded N. by East Turkistan, E. by Great Thibet, S. and S. W. by the Punjaub and Cashmere proper, and W. by Cashmere and Bulti ; area, about 30,000 sq. m. ; pop. about 150,000. The country is ele- vated and rugged, lying mostly between the Karakorum range and the western Himalayas. The river Indus flows N". W. between these ridges, its elevation here being nearly 11,000 ' ft. above the sea. The climate is cold and arid. The soil is sterile, but the slopes, being in- dustriously cultivated, produce wheat, barley, buckwheat, apples, and apricots. The domes- tic animals are horses, yaks, cows, the zho (cross of the yak and the cow), asses, sheep, and goats. The sheep attain great size, and are used as beasts of burden in some parts of the country. Iron, lead, copper, and sulphur are found in considerable quantities. The people of Ladakh are mostly Thibetans. They are mild, good-humored, peaceable, and hon- est, but indolent, given to intoxication, and very sensual. Polyandry prevails among the lower classes. They carry on a trade in wool, used for the manufacture of Cashmere shawls. The country was formerly governed by inde- pendent despots, from whom it was wrested by Gholab Sing, the late rajah of Cashmere, in 1835. Capital, Leh. LADANUM, or Labdanum, a resinous exudation of various evergreen shrubs of the genus cis- tus, principally of the C. Creticus, found in the islands of the Grecian archipelago and the neighboring countries. The purer variety sometimes found in commerce is put up in bladders in masses of several pounds each. The substance readily softens and becomes adhe- sive in the hand. Externally it is dark red, almost black, and internally grayish. It diffu- ses an agreeable balsamic odor, and has a bit- ter and somewhat acrid taste. The common quality is very largely mixed with sand and other foreign matters; it is in spiral-shaped pieces of dark gray color, and hard and brittle. It contains only about 20 per cent, of resin, while in the purer quality 86 per cent, has been found ; the other ingredients are gum and wax, with malate of lime, and in the common quality 72 per cent, of foreign substances. Ladanum, like many other similar drugs, has fallen into disuse ; it was formerly employed in fumiga- tion, and as a stimulant expectorant, and also as an ingredient of plasters. LADD, William, an American philanthropist, born in Exeter, N. H., May 10, 1778, died in Portsmouth, April 9, 1841. He graduated at