Cooley's Cyclopaedia of Practical Receipts Volume I Part 38

_Prop._ Gaseous, colourless, invisible; highly pungent, acrid, irritating and alkaline; irrespirable, unless very largely diluted with air; extinguishes combustion; burns slowly in oxygen; sp. gr. 0589; 100 cub.

inches weigh 1826 gr. Under a pressure of 65 atmospheres, at 50 Fahr., it forms a transparent, colourless liquid of the sp. gr. 0731; at 60 Fahr. this liquid expanded into 1009 times its volume of ammoniacal gas; at -40 Fahr., and the ordinary atmospheric pressure, it forms a subtle colourless liquid, which at -103 Fahr. freezes into a white, translucent, crystalline substance. (Faraday.) It is highly basic; all its salts are either volatilised or decomposed at, or under, a red heat--those with a volatile acid sublime unchanged--those with a fixed acid lose their ammonia. It is decomposed into its elements by transmission through a red-hot tube; and when in contact with metallic oxides or spongy platinum, at the same temperature, the newly evolved hydrogen unites with the oxygen of the oxide or of the atmosphere, forming water. Water at 50 Fahr.

absorbs 670 times its volume of this gas, and the solution has the sp. gr.

0875. Its concentrated aqueous solution boils at 130, and freezes at -40 Fahr.

_Tests, &c._ Ammonia is recognised by--1. Its pungent odour:--2. By turning vegetable blues green, and vegetable yellows brown; but which soon regain their previous colours, especially on the application of heat:--3.

By producing dense white fumes when brought in contact with those of hydrochloric acid:--4. By the Nessler test (see WATER, QUANt.i.tATIVE AND QUALITATIVE a.n.a.lYSIS OF):--5. If a saturated solution of a.r.s.enious acid is mixed with a solution of nitrate of silver (strength 2%) a trace of ammonia causes the formation of try-argentic a.r.s.enite:--6. Bottger says a very delicate test for ammonia is afforded by an aqueous solution of carbolic acid. On adding to a liquid containing the smallest quant.i.ty of ammonia, or an ammoniacal salt, a few drops of this solution, and then a small quant.i.ty of a filtered solution of chloride of lime, the liquid becomes green, especially when warmed.

_Phys. eff., &c._ Inhaled, undiluted with air, it is an irritant poison, producing spasms of the glottis, convulsions, and death; even when diluted it acts as a powerful acrid, and local irritant; applied to the skin it causes vesication. The use of the pungent odour of common 'smelling salts,' in syncope, headache, &c., is well known. Largely diluted with air, it has been recently highly extolled in chronic hoa.r.s.eness, asthma, &c.; and as an antidote to the fumes of bromine, chlorine, and hydrocyanic acid. (Smee.)

_Ant., &c._ The vapour of acetic acid or common vinegar, freely inhaled.

It may be produced by sprinkling a little on a piece of hot iron, as a heated shovel. If bronchial inflammation follows, it must be treated by purgatives and a low diet; and, if severe, and the patient be plethoric or robust, by venesection or cupping.

_Uses._ Ammonia is employed in numerous processes in _chemistry_ and the _arts_; but chiefly in the form of 'liquor of ammonia,' 'spirits of hartshorn,' &c., and in combination, under the form of salts. In its pure or gaseous state it possesses little practical interest.

=Ammonia, Solution of.= _Syn._ SOLUTION OF AMMONIA, LIQUOR AMMONIae, AMMONIUM HYDRATE, AMMONIA, Eng.; AMMONIAQUE LIQUIDE, DISSOLUTION D'AMMONIAQUE, ESPRIT DE SAL AMMONIAC, Fr.; ATZENDER AMMONIUM-LIQUOR, SALMIAK-GEIST, Ger.; LIQUORE DI AMMONIACO, Ital. Ammonia gas readily dissolves in water, one volume of water absorbing about 670 volumes of ammonia, much heat being liberated, and the solution increases greatly in volume.

This solution is regarded in two very different lights; firstly and most generally as simply a solution of gaseous ammonia, a view rendered most probable by its general physical and by many chemical reactions; by a few, however, it is looked upon as a solution of ammonium hydrate.

[Ill.u.s.tration]

Prepared by distilling, in a tubular retort, equal parts of sal ammoniac, hydrated lime, or slaked lime and water, and pa.s.sing the gas evolved through a set of Wolff's bottles partially filled with water, as in the figure above.

[Ill.u.s.tration:

_A_, Cylindrical Iron Retort.

_B_, Furnace for ditto.

_C C C C_, Stoneware Receivers.

_D D D D_, Connecting Pipes.

_E F_, Waste Pipe and Receiver.

_G_, Safety Tube. ]

Commercially this article is prepared on the large scale, from a mixture of about equal parts of fresh-slaked lime and sal-ammoniac or sulphate of ammonia, which is heated in an iron cylinder or retort connected with a set of 'refrigerators,' the latter consisting of a row of stoneware bottles with double necks, containing water, and kept very cold. The general arrangement of the apparatus used in this manufacture is exhibited above, and with the accompanying references, will be easily understood.

The 'condensers,' when in use, are surrounded with cloths (not shown in the _engr._) kept wet with very cold water, whilst constant current of cold air is commonly made to pa.s.s over them. The pipe (_D_) leading from the retort is also several feet long, and is advantageously pa.s.sed through a wooden screen in order that the radiated heat of the retort and brickwork of the furnace may be intercepted as much as possible.

Two different methods of proceeding are adopted in this process. In the one the dry pulverulent ingredients are mixed together, and the resulting gas distilled over into the water placed in the receivers. In the other the lime is made into a 'pap' with water, and the ammonia-salt, in coa.r.s.e powder, being added, the whole is rapidly blended together, before closing the retort, and applying heat. In either case a proportionate quant.i.ty of water is put into the condensers, and the operation is nearly similar; but the latter method requires the least heat, and so far as the receivers and refrigerators are concerned, is, perhaps, the one most easily managed. It is that which is always, and necessarily followed, when sulphate of ammonia is employed.

_Prop., Uses, &c._ Highly pungent, caustic, and alkaline; lighter than water, and presenting in a liquid form most of the characteristics of pure ammonia. When strongest has a sp. gr. of 875, and contains about 39 per cent. of ammonia, but the usual strong ammonia of commerce has a sp. gr.

of but 88. The liquor ammonia fortior, B. P., has a sp. gr. of about 893, and contains 325 per cent. of ammonia, while the liquor ammoniae B.

P. has a sp. gr. of about 940, and contains about 10 per cent. of ammonia. As a medicine it is antacid, diaph.o.r.etic, rubefacient, stimulant, and counter-irritant; and is used in various affections in which these remedies are indicated. As a vesicant it is superior to cantharides, and as a caustic it is used with advantage in the bites of rabid animals, especially those of serpents and insects. Its vapour is a common nasal stimulant in faintings, epilepsy, &c. In its concentrated form it is a corrosive poison.--_Dose_, 5 to 25 drops, in cold water, or milk and water. It enters into the composition of several valuable external remedies, and is in constant employment in the _chemical laboratory_, both as a reagent and for the preparation of other compounds.

_Ant., &c._ When the fumes have been inhaled, the patient should be exposed to a current of fresh air; and when the liquid has been swallowed, vinegar or lemon-juice mixed with water may be administered; followed by an emetic, or, on its failure, by the stomach-pump.

_Estim._ The quant.i.ty of gaseous ammonia in pure water of ammonia is easily determined from the specific gravity of the liquid, or from its saturating power. When impure or mixed with other substances, a given weight of the sample is placed in a small retort, the end of which is made to dip into a vessel containing dilute hydrochloric acid. A strong solution of caustic pota.s.sa is then poured into the retort, and heat applied by means of a small spirit lamp. When _all_ the ammonia is distilled over, the acid solution is evaporated to dryness, by the heat of a water bath, and the residuum (chloride of ammonium) weighed. Each grain of the chloride thus found represents 31804 gr. of pure ammonia; 535 parts of the former being equivalent to 17 of the latter. If the article for examination be a solid substance (as a salt), it may be dissolved in water, or in dilute acid, before being put into the retort.

In accurate experiments in the laboratory, ammonia is usually WEIGHED either as chloride of ammonium (see _above_), or as ammonio-bichloride of platinum (NH_{4}Cl, PtCl_{2}); every gr. of the latter representing 07614 gr. of pure ammonia. Sometimes, though rarely, the quant.i.ty of ammonia is determined from the volume of nitrogen eliminated from it, of which 14 gr.

represent 17 gr. of ammonia.

_Concluding remarks, Patents, &c._ Whatever form or process may be adopted for the preparation of liquid ammonia, it is absolutely necessary to keep the receivers as cool as possible, by means of snow, ice, or a current of very cold water, for the purpose of promoting the absorption of the gas, and to prevent its loss. On the small scale, the gla.s.s receivers or bottles may be most conveniently surrounded with ice, or a freezing mixture, and two, or more of them, should be furnished with safety-tubes, to prevent accidents. On the large scale, a capacious oblong retort, usually of iron (but sometimes, though seldom, of lead), with a large opening or tubulature conveniently situated for inserting the 'charges,'

and withdrawing the residuum of the distillation, is employed. The tubulature, or opening, is closed by means of a large and accurately ground iron stopper, or with a door secured by screws, as the case might be. The stopper is well greased before insertion, and is removed by means of a powerful lever. Should it become so firmly fixed that it cannot be displaced in the usual manner, a cloth moistened with cold water, and carefully wrapped round it, without touching the neck of the retort, will generally cause it to contract sufficiently to enable the operator to remove it with facility. Sometimes a large iron kettle, with a moveable and accurately fitting lid secured in its place like that of a 'Papin's digester,' and having a large and long tubulature in its centre, is employed instead of a retort, over which it has the advantage of exposing a larger opening for the removal of the residuum of the process. In either case the distillatory vessel is imbedded in sand supported by fire-brick, and is not exposed directly to the heat of the furnace. Before commencing the distillation the joints are all well luted, to avoid leakage. An excellent plan is to pa.s.s the gas, as it leaves the retort, through a silver or pewter 'worm' or 'refrigerator' set in a tub supplied with a stream of very cold water; by which it will be sufficiently cooled before it reaches the 'receivers' to obviate the necessity of any further attention to them than keeping the cloths wrapped round them constantly moistened with cold water. The lower end of the 'worm' should be connected, by means of a balloon-shaped 'adopter,' with the 'still,' and the upper end with the first 'receiver,' the use of the balloon being to intercept any volatilised ammonia-salt that might be accidentally driven over by the heat being too high, or too suddenly raised.

The heat should be gradually applied, and very gradually raised, to prevent any of the sal ammoniac or sulphate being volatilised undecomposed; and even towards the end of the process it should not even approach redness.

The lime is best 'slaked' and 'papped' with about 4 parts of water; as a lower heat is then required to expel the gas, and it pa.s.ses over more easily and fully than when less water is employed. This is absolutely necessary when the sulphate is the ammonia-salt used; as otherwise the residuum of 'sulphate of lime' would become so hard that it could not be easily removed from the retort.

The gas being wholly expelled from the retort, or other distillatory vessel, it is disconnected from the receivers, and (when sal ammoniac has been employed) the heat is raised sufficiently high to fuse the residual chloride of calcium, which is then at once baled or poured out. Gla.s.s retorts often suffer fracture at this point; but if they escape now, it generally happens that they are broken when heat is applied for a second operation. Hence, according to Prof. Muspratt, it is rare to find a retort, even when carefully handled, that will stand two operations.

When crude sulphate of ammonia is employed it is advisable to have only a little water in the first receiver, which is placed there merely to purify the gas which pa.s.ses through it, and to retain any traces of volatile empyreumatic or oily matter which may be carried over with it.

Pure solution of ammonia is most easily obtained from 'sal ammoniac,' but crystallised sulphate of ammonia, often crude, is more commonly employed, on account of its lower price.

The preparation of pure solution of ammonia admits of no other improvements than such as merely affect the form of the apparatus employed to produce it; and hence, unlike the ammonia-salts of commerce, has been little meddled with by inventors and patentees. Among the plans having for their object the production of an ammoniacal solution, more or less concentrated, fitted for many of the purposes of the arts, and for the preparation of salts, but not for chemical and medical use, besides those of Reece, Spence, Crane and Jullien, &c., already noticed, may be mentioned--

1. That of Watson (Patent dated 1838) in which gas-liquor mixed with a proper quant.i.ty of fresh-slaked lime is distilled from a s.p.a.cious retort or still into a receiver containing cold water, until much steam pa.s.ses over with the gas, when the strong alkaline liquor forming the distillate, and called the first portion, is drawn off. The distillation is then continued, when a weaker and impurer solution is obtained, called the second portion. The first portion is then reintroduced into a retort or still with a small quant.i.ty of fresh lime, and the distillation repeated.

The product the patentee calls the first portion of the second distillation. The latter is a strong ammoniacal liquor sufficient for all the purposes of scouring, cleaning, conversion into commercial ammonia-salts, &c. It may be further purified by a third distillation; the second portion of each operation being transferred again to the still with the next fresh charge of gas-liquor.

2. A modification of Coffey's still,[43] patented by Mr W. E. Newton (1841), under the name of the 'AMMONIA STILL,' is now extensively and successfully employed in this manufacture. By its use ammonia may be obtained from 'gas-liquor,' 'bone-spirit,' or any other ammoniacal liquor or solution, and even from solutions of the salts of ammonia, of almost any density, and of considerable purity; and this by a process which is continuous and inexpensive. The body of the apparatus is formed of wood, the chambers are lined with lead, and the diaphragms are of perforated sheet iron. The management of the apparatus varies with the form in which it is desired to obtain the product. When the ammonia is required to leave the upper chamber of the rectifier in the form of gas, either pure or impure, the steam which ascends, and the current of 'ammoniacal liquor'

which descends, are regulated in such relative proportions that the latter remains at or near the atmospheric temperature during its pa.s.sage through some of the upper chambers, becoming successively hotter as it descends, until at length it enters into ebullition; in which state it pa.s.ses through the lower chambers, either to make its escape, or to enter a cistern provided to receive it. If, on the contrary, the ammonia is required to leave the upper chamber in combination with the vapour of water, the supply of steam entering below must be in such proportion to that of the ammoniacal liquor supplied from above, that the latter may be at or near the boiling temperature in the upper part of the apparatus.

Crude liquor and ammonia-salts, before being thus submitted to distillation, are, of course, first treated with a proper quant.i.ty of quick-lime--in the one case to remove most of the impurities, and in the other to set the ammonia free by seizing on its acid.[44]

[Footnote 43: An _engr._ and description of this still, as employed for spirit, is given under DISTILLATION (which _see_).]

[Footnote 44: For a full description of the "AMMONIA-STILL," _see_ Newton's 'Patent Journ.,' 'Pharm Journ.,' xiii, 64; &c.]

The water or solution contained in the first bottle or the first receiver is found to be the strongest, provided it has been kept well cooled; and that in the others, of progressively decreasing strength. By mixing the contents of one bottle with another a solution of almost any strength may be made. It is also easy to prepare liquor of ammonia of any required strength, or to ascertain the strength of that in the receivers, by observing the expansion of the liquid. Water, when fully saturated with ammonia, expands from 3 volumes to 5 vols.; and in less, but corresponding proportion, according to the quant.i.ty absorbed. All that is necessary in practice is, that each receiver be furnished with a gauge-pipe by which the degree of expansion may be noted. On the small scale, graduated gla.s.s receivers may be used.

3. Mallet's Apparatus. This, which is employed in many of the large gas works, is shown in vertical section in the accompanying woodcut. Steam is forced into large receptacles, which are filled with gas water, by which means the carbonate of ammonia is volatilised. When lime, as is sometimes the case, is added, ammonia gas is evolved, and this being conveyed into weak sulphuric acid, sulphate of ammonia is the result.

[Ill.u.s.tration]

The apparatus consists of two cylindrical boiler-plate vessels, A and B. A is heated directly by the fire, and has a leaden tube, _c_, which dips into the liquid contained in B, this vessel being so placed as to catch the waste heat from the fire. _b_ and _e_ are man-holes; _a_ and _a'_ are stirrers. By means of the tube _d_ the fluid from B can be run off into A.

Gas-water is poured into both vessels, and lime added; ammonia is liberated, whilst carbonate of lime and sulphide of calcium are formed, and these latter remain in the vessels after the volatilisation of the ammonia. The vessel D is also filled with ammoniacal water, and when the operation is in action this water, already warmed, is run by the aid of the tube _h_ from D into B. E is a gas-water tank, from which D is filled by means of _g_. The ammonia set free in A is, with the steam, conveyed by the pipe _c_ into B, thence through _c'_ into the wash-vessel C, and thence again through _c?_ into the first condenser, D. The partially condensed vapour now pa.s.ses into the condensing vessel F, the worm of which is surrounded by cold water. The dilute ammonia is collected in G, and forced by means of the pump (R) into C, from whence it is occasionally removed by means of a syphon into either A or B. The non-condensed ammoniacal gas is carried from G through a series of Wolfe's bottles, the first bottle (H) containing olive oil, with the object of retaining any hydrocarbons that may be present in the gas; the bottle J contains caustic soda-ley, in order to purify the ammonia and retain impurities; the bottle K is half filled with distilled water. The ammoniacal gas having pa.s.sed through K, is conveyed to the large wooden tank (lined with lead) L, filled with diluted sulphuric acid, if it is intended to prepare sulphate of ammonia, or with water, if solution of ammonia be required. The vessel L is placed in a tank of water; _i_ is a small pipe for introducing acid, while the tube leading to M serves to carry off any unabsorbed ammonia, M being likewise filled with acid.

4. By means of Rose's apparatus, the ammoniacal gas-liquor mixed with one third of slaked lime is heated in a boiler to a temperature of from 96 to 100, the ammoniacal gas evolved being pa.s.sed into hydrochloric acid, and thence through charcoal into vessels containing from 120 to 150 litres of water, which is converted into liquid ammonia of a sp. gr. 0920.

5. In Lunge's apparatus the gas-water is heated in a boiler, and the liberated ammoniacal gas pa.s.sed into sulphuric acid.

Solution of ammonia is now seldom made by the druggist, or on the small scale, the large manufacturing chemists supplying it at a very low rate, and of very superior quality. In the shops it is kept of two or three strengths.

The estimation of the strength of ammonia solutions in commerce is known as ammonimetry, and depends upon their specific gravities. The per-centage richness of solutions of ammonia, or of its carbonates, may be most accurately determined, by ALKALIMETRY. For all the ordinary purposes of commerce, and of the laboratory, the strength of pure solutions of ammonia may, however, be inferred, with sufficient correctness, from their density; and to this the term AMMONIOMETRY is usually restricted.

The specific gravity of the sample being found either by the hydrometer[45] or specific gravity bottle, in the usual manner, its per-centage strength may be seen by inspection of the following _Table_ and the _Table_ on p. 127.

[Footnote 45: An hydrometer specially weighted and graduated for this purpose is called an AMMONIM'ETER, AMMONIOM'ETER, or AMMO'NIA-ME'TER (AMMONIM'ETRUM, AMMONIOM'ETRUM, &c., L.)]

TABLE I.--_Showing the per-centage of_ PURE AMMONIA, _and of_ AMMONIA-WATER _of_ 9000, _in Water of Ammonia, of the given specific gravities, at_ 60 Fahr.

By Dr URE.

------------+------------+----------------+------------ Sp. Gr. by Water of Pure Water, experiment. Ammonia Ammonia, per per cent.