AMMONIA. 
121 
§§ 96-98.] 
strength and free from nitrates or ammonia, the resulting solution may 
be dealt with by a zinc-copper couple, and the ammonia developed by 
the action of the couple directly estimated by titration by a decinormal 
hydrochloric acid, if large in quantity, or by “ nesslerising if small 
in quantity. 
IV.—Acetic Acid. 
§ 96. In the five years ending 1916, 12 deaths (8 males and 4 females) occurred 
in England and Wales from drinking, by mistake or design, strong acetic acid. 
A few cases only have been recorded in medical literature, although there have 
been many experiments on animals. 
The symptoms in the human subject consist of pain, vomiting, and convulsions. 
In animals it causes colic, paralysis of the extremities, bloody urine, and oedema 
of the lungs. The lethal dose for plant-eating animals is about 0-49 gramme per kilo. 
There should be no difficulty in recognising acetic acid ; the odour alone is, in 
most cases, strong and unmistakable. Traces are detected by distilling, neutralising 
the distillate by soda, evaporating to dryness, and treating the residue as follows :— 
A portion warmed with alcohol and sulphuric acid gives a smell of acetic ether. 
Another portion is heated in a small tube of hard glass with arsenious acid ; if acetic 
acid is present, or an acetate, a smell of kakodyl is produced. 
V.—Ammonia. 
§ 97. Ammonia (NH ; >) is met with either as a vapour or gas, or as 
a solution of the pure gas in water. 
Properties. — Pure ammonia gas is colourless, with a strong, 
irritating, pungent odour, forming white fumes of ammonic chloride 
if exposed to hydric chloride vapour, and turning moist red litmus paper 
strongly blue. By intense cold, or by a pressure of 6J atmospheres 
at the ordinary temperature, the gas is readily liquefied ; the liquid 
ammonia boils at 38° ; its observed specific gravity is -731 ; it freezes 
at —57-1°. Ammonia is readily absorbed by water ; at 0° water will 
take up 1000 times its own volume, and at ordinary temperatures 
about 600 times its volume. Alcohol also absorbs about 10 per cent. 
Ammonia is a strong base, and forms a number of salts. Ammonia is 
one of the constant products of the putrefaction of nitrogenous sub¬ 
stances ; it exists in the atmosphere in small proportions, and in every¬ 
thing that contains water. Indeed, water is the only compound equal 
to it in its universality of diffusion. The minute quantities of ammonia 
thus diffused throughout nature are probably never in the free state, 
but combinations of ammonia with hydric nitrate, carbon dioxide, etc. 
§ 98. Uses. 1 —A solution of ammonia in water has many applications 
in the arts and industries ; it is used in medicine, and is an indispensable 
laboratory reagent. 
1 Sir B. W. Richardson has shown that ammonia possesses powerful antiseptic 
properties.— Brit. Med Journ., 1862, 
