This compound is largely used in the preparation of detonators for explosives. It is made by the interaction of mercury, nitric acid, and alcohol.

Somewhat varying proportions of ingredients are given by different writers.

(i) One part of mercury is dissolved in 12 parts of nitric acid of sp. gr. 1345; to the solution 55 parts of 90 per cent. alcohol are added, and the whole is well shaken. After a little time, when an energetic reaction has commenced, 6 parts more of the alcohol are gradually added. At first metallic mercury separates, but it subsequently redissolves, and deposits as mercuric fulminate in flakes.1

(ii) Thorpe2 states that 1 part of mercury is dissolved in 10 parts of nitric acid (sp. gr. 133), and for every kilogram of acid used, 1 litre of alcohol, sp. gr. 0833 (= 902 per cent. by volume) is added. The reaction begins either spontaneously or on slight warming. The operation is carried out either in a tubulated retort, the evolved gases then escaping into a flue, or else in glass balloons placed in an open wooden shed. After the alcohol has been added, the operator avoids the shed till the reaction is complete.

(iii) Marshall gives the following particulars.3 The mercury is first cleaned by squeezing it through wash-leather. 05 Kilo. is weighed into a glass flask, and 55 kilos. of nitric acid (sp. gr. 136) are added. When all the mercury has dissolved, the solution is allowed to cool, and then is poured into a large glass flask containing 5 kilos. of alcohol (90 per cent. strength) which has been warmed, if necessary, to a temperature of 20° or 25°. A reaction sets in almost at once, accompanied by effervescence, and the temperature of the liquid rises rapidly to about 80°; the reaction then moderates, but the temperature goes on slowly rising to 83°. Crystals of fulminate form, and white fumes fill the upper part of the flask. After about ten minutes, red fumes appear, vapours are evolved more rapidly, more solid is formed, and there is a further rise of temperature to about 86°. The reaction then moderates: it lasts altogether twenty to twenty-five minutes.

1 Ber., 1870, 9, 787. 2 "Dict. Applied Chem.," II, 631.

3 "Explosives," 1917 edition, II, 700.

The contents of the flask are then poured into water and washed by decantation until practically all the acid has been removed. The fulminate is now collected on a muslin filter, and the washing continued with distilled water until the liquid passing through is no longer acid to litmus paper. Alcohol of 82 to 85 per cent. strength is sometimes employed for the washing. The yield is generally 1.2 to 13 kilos. of fulminate for each kilo. of mercury.

The fumes given off are poisonous and inflammable: they should be removed by means of a good draught. They are condensed in stoneware vessels; the liquid consists of unchanged alcohol containing ethyl nitrite and nitrate, aldehyde, ether, and other byproducts. It is frequently employed as a partial denaturant for fresh alcohol.

(iv) O. Hagen describes in detail the following procedure, known on the Continent as Alder's method.1

In each of 15 wide-necked flasks of colourless glass, 5 litres capacity, is placed 45 kilos. of water-clear nitric acid (40° Be.= sp. gr. 1.38), and 35-40 grams of granulated zinc are dissolved in each quantity of acid. When the zinc has dissolved, 500 grams of pure mercury, weighed out in a 40-c.c. flask, are added, and the mercury dissolved: in winter the mixture must be heated on a water-bath. To avoid loss through spirting, the flasks are loosely stoppered; and in summer, before adding the alcohol at the next stage, the flasks are cooled with water to prevent too energetic action.

A series of 15 retorts, 50 litres capacity, is arranged with their outlets passing each into an earthenware vessel, provided with a tap at the bottom for removal of condensed fumes, and fitted at the top with earthenware condensation-tubes passing eventually to the open air. In each retort is placed 46 kilos. of 91 per cent. alcohol (by volume) denatured with turpentine, and 30 grams of a saturated solution of copper nitrate (56° Be.). Then the contents of one of the large flasks are added, at a temperature of 20-25°. In a short time the temperature rises, and eventually an energetic reaction sets in, white fumes are evolved, and the fulminate begins to form. When the reaction has moderated, and the fumes have become transparent, with a yellowish-red tinge, the retort is removed and sat asids to cool down well.

1 Z. ges. Schiess- u. Sprengstoffw., 1911, 4, 28, 44.

The contents are then transferred to a large, well-glazed earthenware vessel, the retort being rinsed out with cold water. The precipitated fulminate is filtered off through a linen filter, and washed with alcohol of 82-85 per cent. strength until the washings give no turbidity when well diluted with water. Washing with water alone at this stage is not considered satisfactory, as some ethyl nitrate and nitrite may be left in; alcohol is therefore used at first. Then the washing is completed with water until the specific gravity of the washings is 10, and blue litmus paper is no longer reddened by them.

The fulminate may still contain extraneous impurities such as fibres, woody particles, fragments of cork, and so on. These are removed by sieving through silk gauze (100 meshes per sq. cm.) stretched over one end of a glass cylinder, 25 cm. X 20 cm., which is shaken in about 30 litres of water contained in a vessel of 80-90 cm. diameter. The foreign matters are left behind on the sieve. Before sieving, the fulminate is well stirred up in water with a wooden spatula to allow particles of metallic mercury to settle down.

Finally, the moist fulminate is rubbed down into a finely-divided state by means of a wooden pestle, in a porcelain dish. The product is collected in earthenware jars, and allowed to stand for two days, During this time the fulminate settles down, and the supernatant water can be removed, leaving the residual: final product, which contains about 15 per cent. of moisture.

Condensation of the fumes by means of a cooled lead worm is adopted by Alder, but this is not recommended by Hagen. A luting for the joints of the earthenware tubes is made by grinding up dried clay to a fine powder (passing through a sieve with 25 meshes per sq. cm.), and mixing this with ordinary crude glycerin (28° Be.) to a suitable consistency.

Intermediate products for dyestuffs: alkyl-anilines. - Monomethylaniline, C6H5NHCH3, is produced by heating aniline hydrochloride or sulphate with methyl alcohol under pressure.

In an enamelled autoclave are placed 55 parts of aniline hydrochloride and 16 parts of methyl alcohol (by weight), and the mixture heated during two to three hours at a temperature of 180°. The pressure rises first to about 5 atmospheres, subsequently increasing to 25 with the progress of the reaction. After the pressure has fallen the heating is continued for a further six hours or so at 180°. An excess of milk of lime is then mixed with the products of the reaction, and the methylaniline, together with some dimethyl-aniline and unchanged aniline, distilled off.1

Alternatively, 70 parts of aniline, 42 of methyl alcohol, and 8 of sulphuric acid may be used, the mixture being heated in an autoclave to about 200°, and the free bases separated as before.2

.In another process 140 parts of aniline, 32 of methyl alcohol, and 1 of iodine are heated together for 10 hours at 220°.3

Pure monomethyl aniline has not much technical application. If desired, it can be separated from the product obtained as above by treating the mixed bases with an equivalent quantity of p-toluene sulphochloride and dilute solution of sodium hydroxide. This converts the monomethylaniline and the aniline into the corresponding toluene-sulpho-derivatives, whereas the dimethyl-aniline is not attacked and can be distilled off with steam. The residue is then extracted with sodium hydroxide solution, which does not dissolve the toluene-sulpho-methylaniline. The latter can then be hydrolysed by warming for a short time at 100° with an equal weight of sulphuric acid. On pouring the product into water and adding milk of lime, the methylaniline is liberated, and can be distilled off in a current of steam.4

Pure monomethylaniline is a colourless liquid, boiling at 192°. Its sp. gr. is 0976 at 15°.