Chapter 5

His apparatus had been in operation for several months, in the distillery of Mr. Boulet, at Bapeaume-les-Rouen, when a fire in December, 1881, completely destroyed that establishment. In reconstructing his apparatus, Mr. Naudin has availed himself of the experience already acquired, and has necessarily had to introduce important modifications and simplifications into the process. In the zinc-copper couple, he had in the very first place proposed to employ zinc in the form of clippings; but the metal in this state presents grave inconveniences, since the subsidence of the lower part, under the influence of the zinc's weight, soon proves an obstacle to the free circulation of the liquids, and, besides this, the cleaning presents insurmountable difficulties. This is why he substituted for the clippings zinc in straight and corrugated plates such as may be easily found in commerce. The management and cleaning of the pile thus became very simple.

The apparatus that contains the zinc-copper couple now has the form shown in Fig. 1. It may be cylindrical, as here represented, or, what is better, rectangular, because of the square form under which the sheets of zinc are found in commerce.

In this vessel of wood or iron plate, P, the corrugated zinc plates, b, b', b", are placed one above the other, each alternating with a flat one, a, a', a". These plates have previously been scoured, first with a weak solution of caustic soda in order to remove every trace of fatty matter derived from rolling, and then with very dilute hydrochloric acid, and finally are washed with common water. In order to facilitate the disengagement of hydrogen during the reaction, care must be taken to form apertures in the zinc plates, and to incline the first lower row with respect to the bottom of the vessel. A cubical pile of 150 hectoliters contains 105 rows of No. 16 flat and corrugated zinc plates, whose total weight is 6,200 kilogrammes. We obtain thus a hydrogenizing surface of 1,800 square meters, or 12 square meters per hectoliter of impure spirits of 50° to 60° Gay-Lussac. The raw impure spirits enter the apparatus through the upper pipe, E, and, after a sufficient stay therein, are drawn off through the lower pipe, H, into a reservoir, R, from whence, by means of a pump, they are forced to the rectifier.

The hydrogen engendered during the electrolysis is disengaged through an aperture in the cover of the pile.

As a measure of precaution, the hydrogen saturated with alcoholic vapors may be forced to traverse a small, cooled room. The liquefied alcohol returns to the pile. At a mean temperature of 15°, the quantity of alcohol carried along mechanically is insignificant. In order to secure a uniformity of action in all parts of the spirits, during the period devoted to the operation, the liquid is made to circulate from top to bottom by means of a pump, O. The tube, N, indicates the level of the liquid in the vessel. The zinc having been arranged, the first operation consists in forming the couple. This is done by introducing into the pile, by means of the pump, O, a solution of sulphate of copper so as to completely fill it.

The adherence of the copper to the zinc is essential to a proper working of the couple, and may be obtained by observing the following conditions:

1. Impure spirits of 40° Gay-Lussac, and not water, should be used as a menstruum for the salt of copper.

2. The sulphatization should be operated by five successive solutions of ½ per cent., representing 20 kilogrammes of sulphate of copper per 100 square meters of zinc exposed, or a total of 360 kilogrammes of sulphate for a pile of 150 hectoliters capacity.

3. A temperature of 25° should not be exceeded during the sulphatization.

The use of spirits is justified by the fact that the presence of the alcohol notably retards the precipitation of copper. As each charging with copper takes twenty-four hours, it requires five days to form the pile. At the end of this time the deposit should be of a chocolate-brown and sufficiently adherent; but the adherence becomes much greater after a fortnight's operation.

Temperature has a marked influence upon the rapidity and continuity of the reaction. Below +5° the couple no longer works, and above +35° the reaction becomes vigorous and destroys the adherence of the copper to such a degree that it becomes necessary to sulphatize the pile anew. The battery is kept up by adding every eight days a few thousandths of hydrochloric acid to a vatful of the spirits under treatment, say 5 kilos. of acid to 150 hectoliters of spirits. The object of adding this acid is to dissolve the hydrate of oxide of zinc formed during the electrolysis and deposited in a whitish stratum upon the surface of the copper. The pile required no attention, and it is capable of operating from 18 months to two years without being renewed or cleaned.

Passing them over, the zinc-copper couple does not suffice to deodorize the impure spirits, so they must be sent directly to a rectifier. But, in certain cases, it is necessary to follow up the treatment by the pile with another one by electrolysis. The voltameters in which this second operation is performed have likewise been modified. They consist now (Fig. 2) of cylindrical glass vessels, AH, 125 mm. in diameter by 600 in height, with polished edges. These are hermetically closed by an ebonite cover through which pass the tubes, B' C' and B C, that allow the liquid, E+E-E'+E', to circulate.

The current of spirits is regulated at the entrance by the cock, R, which, through its division plate, gives the exact discharge per hour. In addition, in order to secure great regularity in the flow, there is placed between the voltameters and the reservoir that supplies them a second and constant level reservoir regulated by an automatic cock.

In practice, Mr. Naudin employs 12 voltameters that discharge 12 hectoliters per hour, for a distillery that handles 300 hectoliters of impure spirits every 24 hours. The electric current is furnished to the voltameters by a Siemens machine (Fig. 3) having inductors in derivation, the intensity being regulated by the aid of resistance wires interposed in the circuit of the inductors.

The current is made to pass into the series of voltameters by means of a commutator, and its intensity is shown by a Deprez galvanometer. The voltameters, as shown in the diagram, are mounted in derivation in groups of two in tension. The spirits traverse them in two parallel currents. The Siemens machine is of the type SD2, and revolves at the rate of 1,200 times per minute, absorbing a motive power of four horses.

The disacidification, before entering the rectifier, is effected by the metallic zinc. Let us now examine what economic advantages this process presents over the old method of rectifying by pure and simple distillation. The following are the data given by Mr. Naudin:

In ordinary processes (1) a given quantity of impure alcohol must undergo five rectifications in order that the products composing the mixture (pure alcohol, oils, etc.) may be separated and sold according to their respective quality; (2) the mean yield in the first distillation does not exceed 60 cent.; (3) the loss experienced in distillation amounts, for each rectification, to 4 per cent.; (4) the quantity of essential oils (mixture of the homologues of ethylic alcohol) collected at the end of the first distillation equals, on an average, 3.5 per cent.; (5) the cost of a rectification may be estimated at, on an average, 4 francs per hectoliter.

All things being equal, the yield in the first operation by the electric method is 80 per cent., and the treatment costs, on an average, 0.40 franc per hectoliter. The economy that is realized is therefore considerable. For an establishment in which 150 hectoliters of 100° alcohol are treated per day this saving becomes evident, amounting, as it does, to 373 francs.

We may add that the electric process permits of rectifying spirits which, up to the present, could not be rectified by the ordinary processes. Mr. Naudin's experiments have shown, for example, that artichoke spirits, which could not be utilized by the old processes, give through hydrogenation an alcohol equal to that derived from Indian corn.--_La Nature_.

* * * * *

PLASTIC CARBON FOR BATTERIES.

Max Nitsche-Niesky recommends the following in _Neueste Erfindung_.: Good coke is ground and mixed with coal-tar to a stiff dough and pressed into moulds made of iron and brass. After drying for a few days in a closed place, it is heated in a furnace where it is protected from the direct flames and burned, feebly at first, then strongly, the fire being gradually raised to white heat which is maintained for 6 or 8 hours. The fire is then permitted to slowly go down, and when perfectly cold the carbon is taken out of the furnace.

* * * * *

RECENT STUDIES ON THE CONSTITUTION OF THE ALKALOIDS.

By SAMUEL P. SADTLER, Ph.D.

[Footnote: Introductory lecture, Course of 1883-84, Philadelphia College of Pharmacy.]

The sciences of to-day present, as might be expected, a very different aspect from the same branches of knowledge as they appeared fifty or sixty years ago. It is not merely that the mass of observations in most of these lines of study has enormously increased during this interval. Were that all, the change could hardly be considered as an unmixed benefit, because of the increased difficulty of assimilation of this additional matter. Many would be the contradictions in the observations and hopeless would be the task of bringing order out of such a chaos. The advance in the several branches of knowledge has been largely one resulting from improved methods of study, rather than one following simply from diligence in the application of the old ways.

Let us turn to chemistry for our illustration of this. The chemistry of the last century and the early decades of this was largely a descriptive science, such as the natural history branches, zoology, and botany are still in great part. Reasonably exact mineral analyses were made, it is true, but the laws of chemical combination and the fundamental conceptions of atoms and molecules had not been as yet generally established. Now, this want of comprehensive views of chemical reactions, their why and wherefore, was bad enough as it affected the study of inorganic and metallic compounds, but what must have been the conditions for studying the complex compounds of carbon, so widely spread in the vegetable and animal kingdoms. Their number is so enormous that, in the absence of any established relationships, not much more than a mere enumeration was possible for the student of this branch of chemistry. It is only within the last twenty years that chemists have attained to any comprehensive views at all in the domain of organic chemistry. It has been found possible to gradually range most carbon compounds under two categories, either as marsh-gas or as benzol derivatives, as fatty compounds or as aromatic compounds. To do this, methods of analysis very different from those used in mineral chemistry had to be applied. The mere finding out of percentage composition tells us little or nothing about an organic compound. What the elements are that compose the compound is not to be found out. That can be told beforehand with almost absolute certainty. What is wanted is to know how the atoms of carbon, hydrogen, oxygen, and nitrogen are linked together, for, strange to say, these differences of groupings, which may be found to exist between these three or four elements, endow the compounds with radically different properties and serve us as a basis of classification.

The development of this part of chemistry, therefore, required very different methods of research. Instead of at once destroying a compound in order to learn of what elements it was composed, we submit it to a course of treatment with reagents, which take it apart very gradually, or modify it in the production of some related substance. In this way, we are enabled to establish its relations with well defined classes and to put it in its proper place. Of equal importance with the analytical method of study, however, is the synthetical. This method of research, as applied to organic compounds, embodies in it the highest triumphs of modern chemistry. It has been most fruitful of results, both theoretical and practical. Within recent years, hundreds of the products of vegetable and animal life have been built up from simpler compounds. Thousands of valuable dye-colors and other compounds used in the arts attest its practical value. It may, therefore, seem anomalous when I say that one of the most important of all the classes of organic compounds has not shared in this advance. The alkaloids, that most important class from a medical and pharmaceutical point of view, have until quite recently been defined in the books simply as "vegetable bases, containing nitrogen." Whether they were marsh-gas or benzol derivatives was not made out; how the four elements, carbon, hydrogen, oxygen, and nitrogen, were grouped together in them was absolutely a thing unknown. Chemists all admitted two things--first, that their constitution was very complex, and, second, that the synthesis of any of the more important medicinal alkaloids would be an eminently desirable thing to effect from every point of view. Within the last five years, however, quite considerable progress has been made in arriving at a clearer understanding of these most important compounds, and I shall offer to your attention this evening a brief statement of what has been done and what seems likely to be accomplished in the near future.

It was early recognized that the alkaloids were complex amines or ammonia derivatives. The more or less strongly marked basic character of these bodies, the presence of nitrogen as an essential element, and, above all, the analogy shown to ammonia in the way these bases united with acids to form salts, not by replacement of the hydrogen of the acid, but by direct addition of acid and base, pointed unmistakably to this constitution. But with this granted, the simplest alkaloid formulas, those of conine, C_{8}H_{17}N, and nicotine, C_{10}H_{14}N_{2}, still showed that the amine molecule contained quite complex groups of carbon and hydrogen atoms, and the great majority of the alkaloids--the non-volatile ones--contained groups in which the three elements, carbon, hydrogen, and oxygen, all entered. Hence the difficulty in acquiring a knowledge of the molecular structure of those alkaloids at all comparable with that attained in the case of other organic compounds. Of course synthesis could not be applied until analysis had revealed something of the molecular grouping of these compounds, so the action of different classes of reagents was tried upon the alkaloids. Before summarizing the results of this study of the decomposition and alteration products of the alkaloids, a brief reference to a related class of organic compounds will be of assistance to those unfamiliar with recent researches in this field.

It is well known that in coal-tar is found a series of ammonia-like bases, aniline or amido-benzol, toluidine or amido-toluol, and xylidine or amido-xylol, which are utilized practically in the manufacture of the so-called aniline dye-colors. It is perhaps not so well known that there are other series of bases found there too. The first of these is the pyridine series, including _pyridine_, C_{5}H_{5}N, _picoline_ (methyl-pyridine), C_{5}H_{4}N(CH_{3}), _lutidine_ (dimethyl-pyridine), C_{5}H_{5}N(CH_{3})_{2}, and _collidine_ (trimethyl-pyridine), C_{5}H_{2}N(CH_{3})_{3}. This series is also found in relatively larger proportion in what is known as Dippel's oil, the product of the dry distillation of bones.

The second series is the quinoline series, including _quinoline_, C_{9}H_{7}N, _lepidine_ (methyl-quinoline), C_{10}H_{9}N, and _cryptidine_ (dimethyl-quinoline), C_{11}H_{11}N. The two compounds which give name to these series, pyridine, C_{5}H_{5}N, and quinoline, C_{9}H_{7}N, respectively, bear to each other a relation analogous to that existing between benzol, C_{6}H_{6}, and naphthalene, C_{10}H_{8}; and the theory generally accepted by those chemists who have been occupying themselves with these bases and their derivatives is that pyridine is simply benzol, in which an atom of nitrogen replaces the triad group, CH, and quinoline, the naphthalene molecule with a similar change. Indeed, Ladenberg has recently succeeded in obtaining benzol as an alteration product from pyridine, in certain reactions. Moreover, from methyl-pyridine, C_{5}H_{4}N(CH_{3}), would be derived an acid know as pyridine-carboxylic acid, C_{5}H_{4}N(COOH), just as benzoic acid, C_{6}H_{5}COOH, is derived from methyl-benzol, C_{6}H_{5}CH_{3}, and from dimethyl-pyridine, C_{5}H_{3}N(CH_{3})_{2}, an acid known as pyridine-dicarboxylic acid, C_{5}H_{3}N(COOH)_{2}, just as phthalic acid, C_{6}H_{4}(COOH)_{2}, is derived from dimethyl-benzol, C_{6}H_{4}(CH_{3})_{2}. The same thing applies to quinoline as compared to naphthalene.

We may now look at the question of the decomposing effect of reagents upon the alkaloids. The means which have proved most efficacious in decomposing these bases are the action of oxidizing and reducing agents, of bromine, of organic iodides, of concentrated acids and alkalies, and of heat.

Taking up the volatile alkaloids, we find with regard to _conine_, first, that the action of methyl iodide shows it to be a secondary amine, that is, it restrains only one replaceable hydrogen atom of the original ammonia molecule. Its formula is therefore C_{8}H_{16}NH. From conine can be prepared methyl-conine, which also occurs in nature, and dimethyl-conine. From this latter has been gotten a hydrocarbon, C_{8}H_{14}, conylene, homologous with acetylene, C_{2}H_{2}. Conine, on oxidation, yields chiefly butyric acid, but among the products of oxidation has been found the pyridine carboxylic acid before referred to. The formula of conine, C_{8}H_{17}N, shows it to be homologous with piperidine, C_{5}H_{11}N, a derivative of piperine, the alkaloid of pepper, to be spoken of later; and, just as piperidine is derived from pyridine by the action of reducing agents, so conine is probably derived from a propyl-pyridine. The artificial alkaloid paraconine, isomeric with the natural conine, will be referred to later.

_Nicotine_, C_{10}H_{14}N_{2}, the next simplest in formula of the alkaloids, is a tertiary base, that is, contains no replaceable hydrogen atoms in its molecule. It shows very close relations to pyridine. When nicotine vapor is passed through a red-hot tube, it yields essentially collidine, and, with this, some pyridine, picoline, lutidine, and gases such as hydrogen, marsh-gas, and ethylene. Heated with bromine water to 120°C. it decomposes into bromoform, carbon dioxide, nitrogen, and pyridine. When its alcoholic solution is treated with ferricyanide of potassium it is oxidized to dipyridine, C_{10}H_{10}N_{2}. Potassium permanganate, chromic or nitric acid oxidises it to nicotinic acid, C_{6}H_{5}NO_{2}, which is simply pyridine-carboxylic acid, C_{5}H_{4}N(COOH), and which, distilled over quick-lime, yields pyridine, C_{5}H_{5}N.

Turning now to the non-volatile and oxygenized bases, we take up first the opium alkaloids. _Morphine_, C_{17}H_{19}NO_{3}, is a tertiary amine, and appears to contain a hydroxyl group like phenols, to which class of bodies it has some analogies, as is shown in its reaction with ferric chloride. Its meythl ester, which can be formed from it, is _codeine_, one of the accompanying alkaloids of opium. Besides the methyl derivative, however, others are possible, and several have been recently prepared, giving rise to a class of artificial alkaloids known as _codeines_. Morphine, rapidly distilled over zinc dust, yields phenanthren, trimethyl-amine, pyrrol, pyridine, quinoline, and other bases. The action of strong hydrocholoric acid upon morphine changes it into apomorphine, C_{17}H_{17}NO_{2}, by the withdrawal of a molecule of water. Ferricyanide of potassium and caustic soda solution change morphine into oxidimorphine, C_{34}H_{36}N_{2}O_{6}. When heated with strong potassium hydrate, it yields methylamine.

_Narcotine_, another of the opium alkaloids, when heated with manganese dioxide and sulphuric acid, is oxidized and splits apart into opianic acid, C_{10}H_{10}O_{5}, and cotarnine, C_{12}H_{13}NO_{3}. This latter, by careful oxidation, yields apophyllenic acid, C_{8}H_{7}NO_{4}, and this, on heating with hydrochloric acid to 240° C., yields pyridine-dicarboxylic acid, C_{5}H_{9}N(COOH)_{2}. The base cotarnine also results from the prolonged heating of narcotine with water alone. In this case, instead of opianic acid, its reduction product meconine, C_{10}H_{10}O_{4}, is produced.

_Meconic acid_, C_{7}H_{4}O_{7}, which is found in opium in combination with the different bases, has also been investigated. By acting upon meconic acid with ammonia, comenamic acid is formed, and this latter, when heated with zinc dust, yields pyridine.

If we go now to the cinchona alkaloids, we meet with exceedingly interesting results. _Quinine_, C_{20}H_{24}N_{2}O_{2}, when carefully oxidized with chromic acid or potassium permanganate, yields a series of products. First is formed quitenine, C_{19}H_{22}N_{2}O_{4}, a weak base, then quininic acid, C_{11}H_{9}NO_{3}, then the so-called oxycinchomeronic acid, C_{8}H_{5}N0_{6}, and finally cinchomeronic acid, C_{7}H_{6}NO_{4}. Now the two acids last mentioned are simple substitution products of pyridine, oxycinchomeronic acid being a pyridine-dicarboxylic acid, C_{5}H_{2}N(COOH)_{3}, and cinchomeronic acid, a pyridine-dicarboxylic acid, C_{5}H_{3}N(COOH)_{2}. When distilled with potassium hydrate, quinine yields quinoline and its homologues. The alkaloid has been shown to be a tertiary base.

_Quinidine_ yields with chromic acid the same decomposition products as quinine.

_Cinchonine_, C_{19}H_{22}N_{2}O, the second most important alkaloid of these barks, when oxidized with potassium permanganate, yields cinchonic acid, which is a quinoline-carboxylic acid, C_{9}H_{6}N(COOH), cinchomeronic acid, which has just been stated to be a pyridine dicarboxylic acid, and a pyridine tricarboxylic acid. When cinchonine is treated with potassium hydrate, it is decomposed into quinoline and a solid body, which on further treatment yields a liquid base, C_{7}H_{9}N, which is probably lutidine. It has been found, moreover, that both tetrahydroquinoline and dihydroquinoline, hydrogen addition products of quinoline, are present. When cinchonine is distilled with solid potassium hydrate, it yields pyrrol and bases of both the pyridine and quinoline series.

_Cinchonidine_, when heated with potassium hydrate, yields quinoline also, and with nitric acid the same products as cinchonine.

_Strychnine_ has been found to be a tertiary amine. When distilled with potassium hydrate, quinoline is formed.

_Brucine_ is a tertiary diamine, that is, formed by substitution in a double ammonia molecule. When distilled with potassium hydrate it yields quinoline, lutidine, and two isomeric collidines.