AMMONIA

A chemical compound, called also volatile alkali . This substance, in its purest state, is a highly pungent gas, po e ed of all the mechanical properties of the air, but very condensable with water. It consists of 3 volumes of hydrogen and 1 of azote condensed into two volumes; and hence its density is 0·591, atmospheric air being 1·000. By strong compre ion and refrigeration it may be liquefied into a fluid, whose specific gravity is 0·76 compared to water 1·000. Ammonia gas is composed by weight of 82·53 azote and 17·47 hydrogen in 100 parts. It is obtained by mixing muriate of ammonia, commonly called sal ammoniac, with quicklime, in a retort or still, applying a moderate heat, and receiving the gas either over mercury for chemical experiments, or in water to make liquid ammonia for the purposes of medicine and the arts. Woulfe’s apparatus is commonly employed for this condensation. Ammonia is generated in a great many operations, and especially in the decomposition of many organic substances, by fire or fermentation. Urine left to itself for a few days is found to contain much carbonate of ammonia, and hence this substance was at one time collected in great quantities for the manufacture of certain salts of ammonia, and is still used for its alkaline properties in making alum, scouring wool, . When woollen rags, horns, bones, and other animal substances are decomposed in close ve els by fire, they evolve a large quantity of ammonia, which distils over in the form of a carbonate. The main source of ammonia now in this country, for commercial purposes, is the coal gas works. A large quantity of watery fluid is condensed in their tar pits, which contains, chiefly ammonia combined with sulphuretted hydrogen and carbonic acid. When this water is saturated with muriatic acid and evaporated it yields muriate of ammonia, or sal ammoniac, somewhat impure, which is afterwards purified by sublimation. See Carbonate of Ammonia and Sal Ammoniac . The soot of chimnies where coal is burned contains both sulphate and carbonate of ammonia, and was extensively employed, at one time, to manufacture these salts. In making water of ammonia on the great scale, a cast iron still should be preferred, and equal weights of quicklime and sal ammoniac should be brought to the consistence of a pap, with water, before the heat is applied. In this case, a refrigeratory worm or globe should be interposed between the adopter tube of the capital of the still and the bottles of Woulfe’s apparatus. The muriate of lime, or chloride of calcium, which is left in the still when the whole ammonia is expelled, is of no value. Water is capable of condensing easily about one third of its weight of ammonia gas, or 460 times its bulk. The following table of the quantity of ammonia in 100 parts by weight of its aqueous combinations, at succe ive densities, is the result of very careful experiments made by me, and recorded in the Philosophical Magazine for March, 1821. Table of Water of Ammonia or Volatile Alkali, by Dr. Ure. | Water of 0·900. | Ammo- nia in 100. | Water in 100. | Specific gravity by experi- ment. | Mean specific gravity. | Equivalent primes. | | 100 | 26·500 | 73·500 | 0·9000 | | | | 95 | 25·175 | 74·825 | 0·9045 | 0·90452 | | Wat. Am. | | 90 | 23·850 | 76·150 | 0·9090 | 0·90909 | 24 | + | 76, | 6 | to | 1 | | 85 | 22·525 | 77·475 | 0·9133 | 0·91370 | | | 80 | 21·200 | 78·800 | 0·9177 | 0·91838 | 21·25 | + | 78·75, | 7 | to | 1 | | 75 | 19·875 | 80·125 | 0·9227 | 0·92308 | | | 70 | 18·550 | 81·450 | 0·9275 | 0·92780 | 19·1 | + | 80·9, | 8 | to | 1 | | 65 | 17·225 | 82·775 | 0·9320 | 0·93264 | 17·35 | + | 82·65, | 9 | to | 1 | | 60 | 15·900 | 84·100 | 0·9363 | 0·93750 | 15·9 | + | 84·1, | 10 | to | 1 | | 55 | 14·575 | 85·425 | 0·9410 | 0·94241 | 14·66 | + | 85·34, | 11 | to | 1 | | 50 | 13·250 | 86·750 | 0·9455 | 0·94737 | 13·60 | + | 86·40, | 12 | to | 1 | | 45 | 11·925 | 88·075 | 0·9510 | 0·95238 | 11·9 | + | 88·1, | 14 | to | 1 | | 40 | 10·600 | 89·400 | 0·9564 | 0·95744 | 11·2 | + | 88·8, | 15 | to | 1 | | 35 | 9·275 | 90·725 | 0·9614 | 0·96256 | | | 30 | 7·950 | 92·050 | 0·9662 | 0·96774 | 8·63 | + | 91·37, | 20 | to | 1 | | 25 | 6·625 | 93·375 | 0·9716 | 0·97297 | 7 | + | 93, | 25 | to | 1 | | 20 | 5·300 | 94·700 | 0·9768 | 0·97826 | 6 | + | 94, | 30 | to | 1 | | 15 | 3·975 | 96·025 | 0·9828 | 0·98360 | 4·5 | + | 95·5, | 40 | to | 1 | | 10 | 2·650 | 97·350 | 0·9887 | 0·98900 | 3 | + | 97, | 60 | to | 1 | | 5 | 1·325 | 98·675 | 0·9945 | 0·99447 | |