39S 



NATURE 



[Feb. 27, 1879 



ON A NEW CHEMICAL INDUSTRY ESTA- 

 BLISHED BY M. CAMILLE VINCENT^ 



" A FTER I had made the discovery of the marine acid air, 



■^*- which the vapour of spirit of salt may properly enough 

 be called, it occurred to me that, by a process similar to that by 

 which this acid air is expelled from the spirit of salt, an alkaline 

 air might be expelled from substances containing the volatile 

 alkali. Accordingly I procured some volatile spirit of sal- 

 ammoniac, and having put it into a thin phial and heated it with 

 the flame of a candle, I presently found that a great quantity of 

 vapour was discharged from it, and being received in a basin of 

 quicksilver, it continued in the form of a transparent and per- 

 manent air, not at all condensed by cold. " 



These words, written by Joseph Priestley rather more than 100 

 years ago, describes the experiment by which ammonia was first 

 obtained in the gaseous state. Unacquainted with the composi- 

 tion of this alkaline air, Priestley showed that it increased in 

 Tolume when the electric sparks are passed through it, or when 

 the alkaline air (ammonia) is heated, the residue consists of 

 inflammable air (hydrogen). BerthoUet, in 1788, proved that 

 this increase in bulb is due to the decomposition of ammonia into 

 nitrogen and hydrogen, whilst Henry and Davy ascertained that 

 two volumes of ammonia are resolved into one volume of nitrogen 

 aud three volumes of hydrogen. 



The early history of sal ammoniac and of ammonia is very 

 obscure. The salt appears to have been brought into Europe 

 from Asia in the seventh century, derived, possibly, from volcanic 

 sources. An artificial mode of producing the ammoniacal salts 

 frt m decomposing animal matter was soon discovered, and the 

 early alchemists were well acquainted with the carbonate under 

 the name of spiritus salis urince. In later times sal-ammoniac 

 was obtained from Egypt, where it was prepared by collecting 

 the sublimate obtained by burning camel's dung. 



Although we are constantly surrounded by an atmosphere of 

 nitrogen, chemists have not yet succeeded in inducing this inert 

 element to combine readily ; so that we are still depen- 

 dent for our supply of combined nitrogen, whether as nitric 

 acid or ammonia, upon the decomposition of the nitrogenous 

 constituents of the bodies of plants and animals. This may be 

 effected either by natural decay giving rise to the ammonia, 

 which is always contained in the atmosphere, or by the dry 

 distillation of the same bodies, that is by heating them strongly | 

 out of contact with air, and it is from this source that the world j 

 derives the whole of its commercial ammonia and sal-ammoniac. | 



Coal — the remains of an ancient vegetable world — contains j 

 about 2 per cent, of nitrogen, the greater part of which is ; 

 obtained in the form of ammonia when the coal undergoes the | 

 process of dry distillation. In round numbers 6,ooo,cxx) tons of j 

 coal are annually distilled for the manufacture of coal-gas in this 

 country, and the ammoniacal water of the gas-works contains the , 

 salts of ammonia in solu'ion. 



According to the most reliable data 100 tons of coal when I 

 distilled so as to yield 10,000 cubic feet of gas of specific gravity 

 o'6, give the following products, in tons : — 

 Gas. Tar. Ammonia Water. Coke. 



22-25 8'5 95 5975 Average. 



This ammonia-water contains about 1*5 percent, of ammonia ; 

 hence the total quantity of the volatile alkali obtainable fr m the 

 gas-works in England amounts to some 9,000 tons per annum. 



A singular difference is observed between the dry distillation 

 of altered woody fibre as we have it in coal — and woody fibre itself. 

 In the products of the first operation we chiefly find in the tar 

 the aromatic hydrocarbons such as benzene, whilst in the second 

 we find acetic acid and methyl-alcohol are predominant. 



The year 1848 is a memorable one in the annals of revolu- 

 tionary chemistry, for in that year Wurtz proved that ammonia 

 is in reality only one member of a very larj^e family. By acting 

 with caustic potash on the nitriles of the alcohol radicals, he 

 obtained the first series of the large class of compound animo- 

 nias, the primary monamines. Of these, methylamine is the first 

 on our list : — 



CH, 

 CO 



» N -f 2KOH 



CH, 

 H, 



3 N -t- CO 



OK 

 OK- 



The years that followed, 1849-51, were prolific in ammoniacal 

 discovery. Ilofmann pointed out that not only one atom of 

 hydrogen in ammonia can be replaced by its equivalent of 



• Lecture given at the Royal Institution by Prof. Roscoe, LL.D., F.R.S., 

 February 21, 1879. Revised by the Author. 



organic radical, but that either two or all of the three atoms of the 

 hydrogen in ammonia can be likewise replaced, giving rse to 

 the secondary and tertiary amines by the following simple 

 reactions : — 



H) CH3 



1. CHjI -fH[N = HI-J-H \T\ 



H) H 



CH, ) CH, 



2. CHgl -h H J N = HI + CH3 ^ N 



H ) H 



CHj ) CHg 



3. CH3I -I- CH3 ^ N = HI -f CH3 \ N 



Hi CH3) 



To these bodies the names of methylamine, dimethylamine, 

 and trimethylamine were respectively given. They resemble 

 ammonia in being volatile alkaline liquids or gases, which 

 combine with acids to form crystallisable and well defined salts. 



Hitherto, these compound ammonias have been chemical 

 curiosities ; they have, however, recently become — as has so 

 often been the case in other instances — of great commercial 

 importance, and are now manufactured on a large scale. 



We are all well aware that the French beet-root sugar industry 

 is one of great magnitude, and that it has been largely extended 

 in late years. In this industry, as in the manufacture of cane- 

 sugar, large quantities of molasses or treacle remain behind after 

 the whole of the crystallisable sxtgar has been withdrawn. These 

 molasses are invariably employed to yield alcohol by fermenta- 

 tion. The juice of the beet, as well as that of the sui^ar-cane, 

 contains, in addition to the sugar, a large quantity of extractive 

 and nitrogenous matters, together with considerable quantities of 

 alkaline salts. In our sugar-producing colonies, the waste 

 liquors or spent-w ash from the still — called vinasses in French — 

 are wastefully and ignorantly thrown away instead of being . 

 returned to the land as a fertiliser, and thus the soil becomes 

 impoverished. 



In France it has long been the custom of the distiller to 

 evaporate these liquors (vinasses) to dryness, and calcine the 

 mass in a reverbatory furnace, thus destroying the whole of 

 the organic matter but recovering the alkaline salts of the beet- 

 root. In this way 2,000 tons of carbonate of potash are an- 

 nually produced in the French distilleries. More than thirty 

 years ago the idea was entertained of collecting the ammonia- 

 water, tar, and oils which are given off when this organic 

 matter is calcined, but the practical realisation of this project 

 has only quite recently been accomplished, and a most unex- 

 pected new field of chemical industry thus opened out through 

 the persevering and sagacious labours of M. Camille Vincent, 

 of Paris. 



The following is an outline of the process as carried out at the 

 large distillery of Messrs. Tilloy, Delaune, and Co., at Courrieres. 

 The spent-wash, having been evaporated until it has attained a 

 specific gravity of i'8i, is allowed to run into cast-iron retorts, 

 in which it is submitted to dry distillation. This process lasts 

 four hours, the volatile products pass over, whilst a residue of 

 porous charcoal and alkaline salts is left behind in the retort. 

 The gaseous products given off during the distillation are passed 

 through coolers, in order to condense all the portions which are 

 liquid or solid at the ordinary temperature, and the combustible 

 gases pass on uncondensed, and to serve as fuel for heating the 

 retorts. 



The liquid portion of the distillate is a very complex mixture 

 of chemical compounds resembling, in this respect, the corre- 

 sponding product in the manufacture of coal gas. Like this 

 latter, the liquid distillate from the spent-wash may be divided 

 into — I. The ammonia water; 2. The tar. The ammonia 

 water of the vinasses resembles that of the coal-gas manufacture, 

 in so far as it contains the carbonate, sulphydrate, and hydro- 

 cyanide of ammonia ; but it differs from this (and approximates 

 to the products of the dry distillation of wood) by containing, iii 

 addition, methyl alcohol, methyl sulphide, methyl cyanide, many 

 of the members of the fatty acid series, and, most remarkable 

 of all, large quantities of the salts of trimethylamine. 



The tar, on redistillation, yields more ammonia water, a large 

 number of oils, the alkaloids of the pyridene series, solid 

 hydrocarbons, carbolic acid, and lastly, a pitch of fine quality. 



The crude alkaline aqueous distillate is first neutralised by 

 stilphuric acid, and the saline solution evaporated, when crystals 

 of sulphate of ammonia are deposited, and these, after separat- 

 ing and draining off, leave a mother-liquor, which contains the 

 more soluble sulphate of trimethylamine. During the process of 



