2 On the Manufacture of Alcohol from Coal gas. {CHEMICAL NEWS, Jan. 3, 1863. moistened with the acid. When the acid no longer hydrogen depends evidently, in the first instance, on the absorbs smoke, the body impregnated with it may be nature of the coal distilled, and afterwards upon the washed for the purpose of extracting it; and this weak-manner in which it is distilled. If certain old and not ened acid gives alcohol on distillation. Before delivering the ordinary lighting gas for the purpose of being consumed, it may be treated by this method." The specification of the patent is drawn up in such singular terms, that it is clear M. Castex's knowledge of chemistry is not very extensive. As to making use of lighting gas before its consumption for the production of alcohol, it is a perfect impossibility. The gas would no longer give any light; and we do not recommend gas companies to make any use of the idea broached by M. Castex, for the consumers would soon rise in arms against the application of such a process. The patent was taken out by M. Castex on the 8th of December, 1854; and on the 15th of January, 1855 that is to say, little more than a month afterwards-M. Bertholet explained for the first time to the Académie des Sciences his mode of producing alcohol synthetically. The nearness of these two dates may give rise to some reflections, from which we abstain, because we have not now to examine the question of the validity of the patent. For the scientific world, M. Bertholet is the first author of the discovery; and the silence of M. Castex is a mode of acquiescence which has some importance. Let us now speak of the experiments of our celebrated chemist. It is not with smoke that M. Bertholet produced alcohol, but from the bicarburetted hydrogen, or olefiant gas. He introduced into a flask twenty-six litres of this gas, a quantity of concentrated sulphuric acid, and three kilogrammes of mercury-the use of which in the operation is, we apprehend, for the purpose of minutely dividing the particles. He then agitated the whole together for a considerable length of time. After about 53,000 agitations, it was found that the whole of the gas had been absorbed by the acid, and that a real combination was formed, producing an acid, to which the name of sulpho-vinic or sulpho-ethylic was given. In treating this acid with water, a new reaction was produced. The bicarburetted hydrogen set at liberty combined in its nascent state with water, forming alcohol, leaving the sulphuric acid combined with the addition of a certain quantity of water-that is to say, diluted-and, according to the formula of equivalents, we have CH+2HOCHO2. The alcohol produced is expelled from the liquid by heat. Up to the present time, M. Bertholet has made no attempt practically to utilise this curious experiment. Possibly, he was frightened by the difficulty which attended the absorption of carburetted hydrogen by even the most concentrated sulphuric acid; and he has contented himself with sending to the International Exhibition a litre of alcohol thus produced from its elements, which may be seen in the glass case of M. Ménier, No. 204, Class II. of the French Department. What M. Bertholet has not attempted, M. Cotelle, of St. Quentin, has since realised. Like M. Castex, he has had the idea of employing coal-gas for the production of alcohol, but not before using it for the purpose of giving light. Coal-gas, well purified, contains light carburetted hydrogen, bicarburetted hydrogen, carbonic oxide, hydrogen, and certain carburets, more or less well determined-such, for example, as a trace of propylene, aniline, and even, perhaps, of acetylene. Of these various gases or vapours, the bicarburetted hydrogen is, with propylene, the sole useful element for the purpose proposed. Unfortunately, it exists only in very small proportions. The richness of coal-gas in bicarburetted very numerous analyses are to be relied upon, the proportion of bicarburetted hydrogen may be from 8 to 12 per cent.; but under the conditions in which the manufacture now takes place, we consider these figures as much too high, and believe that 3 or 4 per cent. at the utmost would be much nearer the truth. We speak of the gas manufactured in retorts from the coals of Belgium and the north of France. As to the gas manufactured in coke-ovens, we do not believe it has yet been analysed. However this may be, the following is the method which M. Cotelle appears to have adopted :— After having indicated in his patent many means which he has probably tried, he condenses the gas, and purifies it completely from its sulphuretted hydrogen and ammonia, and finally passes it through concentrated sulphuric acid, which dehydrates it as much as possible. By means of a pump or exhauster, the gas is directed to the base of an earthenware or glass column, filled with plates or diaphragms, pierced with small holes, upon which the sulphuric acid at 66° descends, and which is, consequently, minutely divided. The column which M. Cotelle used when we witnessed the operation, had only fourteen plates or diaphragms, and a single passage of the acid did not suffice to absorb all the bicarburetted hydrogen of the gas, and, at the same time, to saturate all the acid. According to the inventor, a cascade of six plates would be required to accomplish these two objects at one operation-the absorption of all the bicarburetted hydrogen, and the saturation of the sulphuric acid. Let us suppose this desideratum obtained. The carburetted hydrogen and the propylene are absorbed in the column, and there remains from 96 to 97 per cent. of light carburetted hydrogen, hydrogen, and oxide of carbon, without value for the purpose of giving light, but capable of being used for the purpose of heating. It is principally with the object of so using them that the pump or exhauster is required, so that the gas may be drawn off or propelled in any direction without increasing the pressure upon the retorts. The sulpho-vinic, or sulpho-ethylic acid, which M. Cotelle calls his vinasse, is treated with five times its volume of water, and the mixture is then submitted to the action of a current of steam, which carries with it the alcohol produced. These vapours are condensed, and the alcoholic liquor is obtained. This is distilled on a little lime to saturate the sulphuric acid which has been carried with it, and the products of this distillation are rectified, and alcohol of 90° is obtained. The sulphuric acid which has been diluted by the operation so as to reduce it to 20° or 25° of strength, must be concentrated to 66° if required to be used over again, or some other use must be found for it in its diluted state. This use of it, advantageously if it is possible, involves the establishment of another factory on a large scale, even for a distiller producing 30 hectolitres (660 gallons) per day; for the quantity of sulphuric acid at 66° to be employed is considerable. It amounts to about 1500 kilogrammes (30 cwt.) of acid for each hectolitre (22 gallons) of alcohol produced, or 45,000 gallons (45 tons) of acid for 30 hectolitres (660 gallons) of alcohol. Should it be desired to concentrate the diluted acid, apparatus must be provided such as is used in the sulphuric acid factories. This, truly, is not a manufacturing impossibility; but what will be the cost of concentrating for 1500 kilogrammes of acidthat is to say, for one hectolitre of alcohol? CHEMICAL NEWS, Jan. 3, 1863. } On the Preparation of Artificial Mineral Waters. This expense of concentration appears to us, in the actual state of chemical industry, to be a grave difficulty in the way of the success of the new process, even when the complete absorption of the bicarburetted hydrogen is easily effected, as well as the simultaneous saturation of the sulphuric acid; and we are quite sure that it would be necessary to make a new estimate of the cost price which the journals of St. Quentin, with laudable zeal, but with too much precipitation, had fixed at 25 francs per hectolitre of alcohol of 90°. Any serious estimate of the cost price must have been premature, as M. Cotelle was not provided with suitable apparatus to determine it. 3 it disengaged acetylene, and, thrown on a heated metallic plate, a louder explosion resulted than with pure acety lide, and without deposit of carbon. This difference will be readily understood, for the acetylide formed during my experiments, finding itself in presence of excess of oxide of copper, the carbon and hydrogen of the acetylide were entirely destroyed. It is evident that copper, in presence of air and acetylene, is spontaneously transformed into acetylide of copper containing excess of oxide. As lighting gas contains acetylene, a little air, and perhaps even some ammoniacal vapours, it is obvious that acetylide of copper may be formed in tubes which have served to conduct lighting gas.-Comptes Rendus. PHARMACY, TOXICOLOGY, &c. On the Preparation of Artificial Mineral Waters.* (Concluded from pagé 295.)" Sulphurous Waters. Twenty-five francs per hectolitre for alcohol of good taste (it is said to be exempt from all empyreumatic flavour), the selling price of which was 70 francs! Here was enough to set all the speculators in a ferment, and to cause serious reflections to all distillers, and even the manufacturers of sugar and agriculturists. Purchasers presented themselves from all quarters, anxious to treat with M. Cotelle for his patents, French as well as foreign, on condition, be it well understood, that he satisIn the preparation of artificial sulphurous waters for fied them on the subject of cost price. The French patent drinking purposes, it is recommended to employ the was sold, it is said, for 20,000 francs, and the English one crystallised monosulphide of sodium, and it is stated for 480,000 francs. A company was formed at St. Quentin, that it is unnecessary and objectionable to pass free with a capital of 16,000 francs, which was subscribed in sulphuretted hydrogen into the solution. The atmoan hour, for the purpose of constructing a real manufac-spheric air dissolved in the water is always sufficient to tory, and solving the problem on a manufacturing scale. effect the decomposition of some of the sulphide of Since then-that is to say, about two months ago-the sodium, and set free some sulphuretted hydrogen. We enthusiasm has abated, the matter has been examined extract the formula for Baréges water, to show the dose with more sang froid, and it is generally admitted that of sulphide of sodium prescribed: the cost price can only be ascertained as the result of a manufacture on a practical scale, and not by approximative experiments in a laboratory. (To be continued.) On the Formation of Acetylide of Copper in Copper Acetylide of copper having the property of detonating by an elevation of the temperature or by a blow, and the presence of acetylene in lighting gas having been recently proved by M. Berthelot, I have tried to ascertain whether acetylene, in presence of air, could combine with copper, and so form acetylide of copper. By passing a mixture of air and moist acetylene through a glass tube containing bright copper turnings, this metal tarnishes rapidly, assumes iridescent colours, and finally becomes black; but as this alteration takes place only on the surface of the metal, it is very limited. Baréges Water. Sulphide of sodium, crystallised Chloride of sodium . 0'2co grammes. • 0*100 Dissolve the sulphide of sodium in the water, then add the sulphur, and heat gently until the latter is dissolved. The solution obtained in this way will contain exactly 100 grammes of penta-sulphide of sodium, which is sufficient for a bath. Products derived from Mineral Waters. The substances derived from mineral waters which are employed in medicine may be arranged in two classes. The first comprises the deposits formed spontaneously, either on the soil in the neighbourhood of the springs, or in wells or basins in which the water is confined. In the second class may be placed the saline products obtained by the evaporation of the waters. By using copper reduced by hydrogen, I extended the surface of the metal. A small quantity of metal was placed in two flasks containing a mixture of equal volumes of air and acetylene, and also in one of the flasks a drop of ammonia. The two flasks, well stoppered, their necks plunged in water, were left to themselves for two days. They were then carefully opened, and the water entering them absorbed nearly half the gaseous volume. The absorption seemed to be somewhat greater in the flask containing a little ammoniacal vapour. The copper turned black. After washing and drying, I found that it contained a notable quantity of acetylide of copper; for, heated with hydrochloric acid, t. xli. p. 370-410. Chemists have always recognised the fact, that the extraction of all the salts in a mineral water, and with the molecular arrangement assigned to them by Nature, is an operation beyond our art. By submitting a natural water to a moderate temperature, it loses the character Abridged from a Report to the Société de Pharmacie of Paris, by MM. Chatin, Poggiale, and Lefort. Journal de Pharmacie et de Chimie, of a natural water, and can only be considered as a solution of artificial salts; for the mode of combination of acids and bases has been completely changed by the evaporation of the liquid and the volatilisation of the gas. The salts, therefore, even when obtained from the natural source, as at Vichy, can only be looked on as artificial products." CHEMICAL NEWS, Jan. 3, 1863. known in chemistry for about thirty years. Between 1845 and 1850 I constantly worked on aniline to see what results could be produced from it. In 1859, or early in 1860, I discovered the peculiar properties of aniline in combination with arsenic acid. They produced a very brilliant dye, which is now called " magenta." I patented the discovery, and afterwards found out that Dr. Medlock had conse-purchased Dr. Medlock's patent. previously patented the same thing. Our firm afterwards have mentioned no such colour had been produced by Before the time I aniline and arsenic acid. I was then, and am now, satisfied of the novelty of the invention. (A copy of Medlock's specification was here put in, and read to the Court). By the process described magenta colour is produced, which, by treatment with different preparations, gives different shades of colour. In my judgment this process was new. Bicarbonate of soda, prepared with care, is, quently, to be preferred to Vichy salts for the preparation of Vichy pastilles or soda lozenges, and the authors recommend the following formula: Bicarbonate of soda Powdered sugar Gum Tragacanth Water 36 grammes. The above mass is flavoured by the following mixture of The colour is largely used, and has become a very valuable essences: Simpson and Others v. Wilson and Another. THIS was an action, directed by the Court of Chancery, to try the validity of Medlock's patent for improvements in the preparation of red and purple dyes. (See CHEMICAL NEWS, vol. vi. page 302.) The declaration, after stating that Medlock's patent is now the property of the plaintiffs, alleged that the defendants had infringed the said patent, by manufacturing and selling a red dye of the colour, commonly known as magenta or roseine, made according to the process described in the specification of the said patent. To which the defendants pleaded 1. Not guilty. 2. That Medlock was not the first and true inventor. 3. That the manufacture was not new. 4. That the manufacture was not new, nor an improvement in any way useful or beneficial to the public. 5. That the patentee did not, within six calendar months after the date of the patent, file an instrument in writing, particularly describing the nature of the invention, and the manner in which it was, or might be, performed. Counsel for the plaintiffs, Sir Fitzroy Kelly, Mr. Grove, Q.C., Mr. Bovill, Q.C., Mr. Drewry, and Mr. J. A. Russell. For the defendants, Mr. Hindmarsh, Q.C., and Mr. Day. In the absence of Sir F. Kelly the case was briefly opened by Mr. Grove, after which the following evidence was called for the plaintiffs : Mr. G. C. Nicholson (examined by Mr. Bovill): I am one of the plaintiffs, and a member of the firm of Simpson, Maule, and Nicholson, manufacturing chemists, of the Atlas Works, Newington. I have given much attention to the study of chemistry and the preparation of dyes. I conduct the chemical department of our business, and am well acquainted with the body called "aniline." It is an oily basic liquid produced from coal tar, and has been article *. I know Heilman's patent. (See CHEMICAL NEWS, vol. vi., p. 302). My attention has been drawn to it since this action was brought. (Specification put in). That patent professes to treat aniline with various salts and substances,-200 at least, but it may include 500. I have tried several of the things mentioned; an immense number of them produce no colour whatever. A person what it was produced the colour according to that speciwould have had to work, perhaps, six months to find out fication. It was only a provisional specification; and no one was aware of it except the Clerk of the Patents. Arsenic acid is a combination of metallic arsenic with five equivalents of oxygen, and containing water of constitu tion, not water mechanically mixed with or adhering to it. The water is in chemical combination with it. Anhydrous arsenic acid is arsenic acid absolutely free from water. Lord Chief Justice Cockburn: You start with saying that arsenic acid is a combination of the metal with oxygen-Witness: And water. Lord Chief Justice Cockburn: Well, suppose you want to distinguish dry arsenic acid from the arsenic acid you have been speaking of, what would you call it?-Witness: I should call that dry arsenic acid-that which I have just mentioned: the combination of arsenic, oxygen, and water is dry. Lord Chief Justice Cockburn: Then there is no difference between arsenic acid and dry arsenic acid ?-Witness: No. Mr. Bovill: The distinction is between anhydrous and dry. that from which the water, which has been mechanically Lord Chief Justice Cockburn: You do not mean by dry united with it, is removed?-Witness: I should call this dry, my lord (holding up a bottle of arsenic acid). In Mr. Bovill: Although it contains water ?-Witness: drous acid is that from which all water has been driven Yes; water as part of its chemical constitution. Anhyoff. The term "anhydrous" implies, free from water. our process we use what is called dry arsenic acid, which means arsenic acid that contains a certain proportion of dissolving arsenious acid-the white arsenic of commerce water in its constitution. Arsenic acid is produced by solidifies into a dry powder. In boiling down, a large -in nitric acid, and boiling the solution down until it quantity of water is driven off, and that brings it to the state of what we call dry arsenic acid, leaving, still, a certain portion of water. tinctly understand you. You say that the driving off the Lord Chief Justice Cockburn: Let me see that I disacid?-Witness: Yes, my lord. quantity of water brings the acid to the state of dry arsenic Mr. Bovill: Which still contains a certain portion of water which is not driven off?-Witness: Yes, exactly. chemical combination?-Witness: Yes. Lord Chief Justice Cockburn: That is, it retains it in By Mr. Bovill: The portion of water driven off in boiling It is necessary for us to remark here that our report is confined to the chemical evidence. CHEMICAL NEW Jan. 3, 1863. Court of Queen's Bench. was, in mechanical combination, water of solution. We cannot produce any effect on aniline by arsenic acid until water is driven off down to the point at which it becomes dry arsenic acid. Arsenious acid will not do it; but if we take arsenious and nitric acids, and drive off the water, we produce dry arsenic acid, which will act on aniline. By Lord Chief Justice Cockburn: Arsenious acid is converted into arsenic acid by the action of nitric acid. The nitric acid parts with a portion of its oxygen, which is superadded to the arsenious acid, and then we get arsenic acid. The water driven off in boiling is not that which enters into chemical combination-it is water of solution or in mixture. Lord Chief Justice Cockburn: Suppose you did not drive the water off at all, but having got arsenic acid you used it without going on boiling-Witness: We should not get colour until we boiled it down for the purpose of getting all the mechanical water, if I may so speak, out of it. Lord Chief Justice Cockburn: You must get it into a dry state-Witness: We must get it into a dry state prior to the dye being formed. Lord Chief Justice Cockburn: Then you must get it it into an anhydrous state, must you not?-Witness: No, certainly not. Lord Chief Justice Cockburn: Not if you drive the water off?-Witness: The mechanical water, I am speaking of. Lord Chief Justice Cockburn: However, you say you get no results until you come to the dry arsenic acid Witness: Until we boil off the water of solution from dry arsenic acid. By Mr. Bovill: No water but that in the nitric acid is used in making arsenic acid; and all of this is driven off except what remains in chemical combination. Mr. Bovill: Now then, in using the dry arsenic acid with aniline, after you have produced it, do you use the dry arsenic acid for the purpose of producing colour? Witness: We do not mix the dry arsenic acid with aniline. Mr. Bovill: Just describe the process.-Witness: Having got our dry arsenic, we mix it with aniline, and heat the mixture. The application of heat produces the melted mass which contains the magenta dye, and which, when dissolved in water and boiled down, produces the pure solid magenta. I should say that any nitric acid in the mixture would have no effect in producing the dye. Lord Chief Justice Cockburn: What I understood you to say just now was this:-If you take arsenious acid and nitric acid, and combine those with heat, you will get, as you say, arsenic acid, the nitric acid parting with a portion of its oxygen, and increasing the strength of arsenious acid until it brings it up to the state of arsenic acid. Then, as I understand, before that combination will act on aniline to produce the dye, you must drive off the superfluous water of solution, so as to bring the arsenic acid to the state of dry arsenic acid?-Witness: Exactly so, my lord. By Mr. Bovill: If any person were to take arsenious acid, nitric acid, and aniline, and put them all together, I do not think any effect at all would be produced; but, when the three are subjected to heat until the water is driven off, the dye would be produced, if the operation were conducted properly if done improperly, it would blow your head off. The dye is produced, because in that process the arsenious acid is converted into dry arsenic acid. Mr. Bovill: Does your lordship follow it? Lord Chief Justice Cockburn: I do not, indeed. I have attended to it, but I have not been able to understand it. Sir F. Kelly: There are three states of this arsenic acid; the one with the water belonging to it in the operation, which, when the water is driven off, becomes dry arsenic acid. Then, to make anhydrous, the small quantity of water which is in chemical combination must be got rid of also; but for the purpose of this operation it is quite enough if you make it dry, which is not, strictly speaking, 5 anhydrous, yet, for all the purposes of commerce and of this manufacture, is dry. Mr. Bovill: Then, as I understand it now, you produce the dye by taking the dry arsenic acid and mixing it with aniline?-Witness: Yes. Mr. Bovill: You may equally make the dye by procuring arsenious acid, aniline, and nitric acid, mixing them together, and then driving off the water; and the reason why you produce it is, the water being driven off, you leave dry arsenic acid-not dry to the sense of touch, but chemically dry arsenic acid?-Witness: Yes. Mr. Bovill: And what is it produces the colour? Is it the action of dry arsenic acid on the aniline ?-Witness: Yes, it dehydrogenates the aniline. There is no difference between the processes, whether you take dry arsenic acid and mix it with aniline, or take the two things from which arsenic acid is made. Lord Chief Justice Cockburn: In fact, in the one instance you start with dry arsenic acid already prepared, and in the other you prepare it in the first stage of the operation. By Mr. Bovill: The addition of a metallic oxide in a mixture of the three would produce no effect as regards the colour. There was no process before by which the colour could be produced so beautiful and so cheap. Many thousand gallons of it are sold. Cross-examined by Mr. Hindmarsh: I am well acquainted with the various modes of producing this dye. One of the colours produced is old, the other new. The purple was new at the date of this patent. The red had formerly been prepared. The processes in use before consisted, to the best of my belief, in the application of two oxidising agents, nitrate of mercury and nitric acid. I have read the various patents relating to the production of the colour. They are very numerous. I believe only two relate to the use of oxides. Bichromate of tin will not produce the colour. I have read a specification of Brooman's, in which he proposes to use a good many anhydrous salts. I believe I have read another in which he proposes to use anhy. drous bichromate of tin. Bichloride of mercury is not an oxidising agent; it contains no oxygen. It may, perhaps, be a dehydrogenating agent. Iodine and five hundred other things have been so described. Arsenic acid was used in cotton print works before the date of this patent. I have never seen it used, but I know it is used as a discharge in place of tartaric acid. The mode of making arsenic acid I have described is mentioned in books on chemistry. 1 do not remember that the result is, in Graham's book, described as a perfectly anhydrous acid. Mr. Hindmarsh: So far as you know, is there any book which describes the making of arsenic acid, which would not produce the material positively dry or anhydrous? Witness: I do not know. Sir F. Kelly: That is rather a comprehensive question. If we are to have the book put in, in which the manufac ture has been described, I apprehend the passages should be read in order that we may understand the question; but to ask the contents of every chemical book is too comprehensive.-Witness: One book will contradict another. Lord Chief Justice Cockburn: Do you know of any process given in scientific works on chemistry in which nitric acid is used where the result would not be anhydrous?-Witness: If I were to perform the operation I should produce a dry arsenic acid. Lord Chief Justice Cockburn: The question put by Mr. Hindmarsh relates not to dry but anhydrous acid.-Witness: Let me read the passage: "This acid is obtained by heating powdered arsenious acid in a basin with an equal quantity of water, and adding to the mixture at the boiling point nitric acid in small quantities so long as ruddy fumes escape. An addition of hydrochloric acid is generally made to increase the solubility of the arsenious acid, but it is not absolutely necessary. The solution of arsenic acid is then evaporated to dryness to expel the remaining nitrie and hydrochloric acids, but the dry mass is not heated above the melting point of lead, otherwise oxygen gas is emitted, and arsenious acid reproduced." I say that, if I were to perform the experiment according to these instructions, I should get, according to the temperature I used, dry arsenic acid or the anhydrous acid. Mr. Hindmarsh: You stopped short; go on with the passage.-Witness reading: "Arsenic acid thus obtained is milk-white and contains no water." That is not absolutely correct. It may be white, and contain water or no water. When nitric acid and arsenious acid are mixed together there may be no nitric acid or arsenious acid present: they may destroy each other. Nitrous and arsenic acids are formed. It is not necessary to apply a high degree of heat to drive off the nitrous acid. There may be something wrong in the description given by Mr. Graham. I know "Fownes' Chemistry." I do not know the process given for making arsenic acid. (Book handed up and description read.) "Powdered arsenious acid is dissolved in hot hydrochloric acid, and oxidised by the addition of nitric acid, the latter being added as long as red vapours are produced: the whole is then cautiously evaporated to complete dryness.' We may differ about the complete dryness. If aniline is mixed with dry arsenic, and the mixture is allowed to stand, no colour will be produced, nor would there if water was present. The application of heat is necessary for the production of the colour. If the arsenic acid were anhydrous, practically no colour would be produced. Medlock's process, as we perform it, produces the colour. On the large scale, we do not boil the arsenic acid to dryness-to an absolute powder, or perfect dryness. We use it in a fluid state. We mix, in fact, a solution of dry arsenic acid and aniline together. The weight of water present is considerably less than that of the arsenic acid. There is about 30 per cent. of water and 70 per cent. of arsenic acid. The presence of water at the time of mixing is not absolutely essential to ensure success. " By the Lord Chief Justice Cockburn: We use water, because it is not so dangerous to the workman; it is more convenient, and it is cheaper. We do not get more dye, but it saves the expense of boiling down. By Mr. Hindmarsh: It is essential that an arseniate of aniline should be formed in the process; but mechanical water is not necessary for the formation of the arseniate. I am quite sure that I have made arseniate of aniline with out water. By the Lord Chief Justice Cockburn: The bottle I have in my hand contains dry, but not anhydrous acid, and I can produce arseniate of aniline by mixing it with aniline. The water present is water of constitution, but not mechanical water, and the whole of it enters into the aniline to form arseniate of aniline. Mechanical water would not combine with the arseniate of aniline produced. By Mr. Hindmarsh: I do not know in what proportions arsenic acid and aniline unite to form arseniate of aniline. We use in practice about equal proportions. The whole of the arsenic acid, practically, is then converted into arseniate of aniline. There may be free aniline. I do not know to a per centage how much water there is in what we call dry arsenic acid. Our workmen know the exact point at which to stop the boiling. Arsenic acid is very deliquescent, and rapidly absorbs water from the atmosphere. Mr. Hindmarsh: Suppose arsenic acid to be made either according to Graham or Fownes, and you wanted to keep it dry, would you not exclude the atmosphere from it?-Witness: According to Graham, it is anhydrous, and, therefore, I do not think it necessary to exclude the atmosphere. Mr. Hindmarsh: Does he not say it absorbs moisture? -Witness: That may be an error. Mr. Hindmarsh: But does he not say so?-Witness: It cannot be anhydrous, and yet have a great affinity for water-I am speaking of anhydrous arsenic acid. Mr. Graham may be mistaken. I applied for a patent, Lut, as far as I recollect, I did not mention solution of arsenic acid. In substance, unquestionably, I mentioned solution of arsenic acid, because I found that answer my purpose at the time. Mr. Hindmarsh: Is not this what you described? "In carrying out this invention, I take a strong solution of arsenic acid, to which I add aniline, toluidine, cumidine, or mixture of the same. I then heat the mixture in a still, or other convenient vessel, until the colour is sufficiently developed."-Witness: That is my provisional specification. I have made the colour with dry arsenic acid. I cannot recollect whether I added water to the experiment. Dry arsenic acid is not mentioned in my specification. Some months after we purchased Medlock's patent, I became aware of Delaire and Girard's process. They propose to use definite quantities of arsenic acid, aniline, and water, and apply heat to the mixture (see CHEMICAL NEWS, vol. vi., p. 314), for the purpose of converting aniline into a red dye. I have tried the process experimentally with certain definite quantities of aniline, arsenic acid, and water. When the whole of the water is driven off, the result is, to convert substantially the whole of the aniline into red dye. Substantially, we use that process. We do not use the exact proportion of water the patent states; we use the smallest quantity we can possibly do with, which saves time in boiling off. The use of water is not necessarily essential to the conversion of acid and aniline into the arseniate of aniline. The arseniate of aniline would be formed whether the arsenic acid was in a solid or a liquid state. It is easier and cheaper to use the liquid solution of arsenic acid, and it is less dangerous than it is to boil that liquid down to a dry state. The main point is saving the men's health, but I admit that it is a little cheaper. Re-examined by Sir F. Kelly: Dry arsenic acid is known as an article of commerce. We had manufactured and sold it before the date of Medlock's patent. I believe it is largely used in calico-printing. We do not mix that dry arsenic acid with aniline. Practically, we use the solution-the dry arsenic acid in solution in water. Lord Chief Justice Cockburn: Does it continue, when in a state of solution, to be dry arsenic acid ?-Witness: No, my lord. Sir F. Kelly: Dry arsenic acid is still in existence, though in a state of solution. Lord Chief Justice Cockburn: No, no; arsenic acid in solution is not dry arsenic acid. so. Sir F. Kelly: It is dry; at least, so we consider. Sir F. Kelly: If your lordship will allow me, I think I can show that it is. The distinction is as perfect as possible. (To the witness): In the solution, does the water at all combine with what you call "dry arsenic acid"?. Witness: No more than in a solution of common salt in water. Lord Chief Justice Cockburn: The solution implies that it is only a mechanical combination. Sir F. Kelly: Whereas, the water which exists in the dry acid, and which distinguishes it from anhydrous, is in chemical combination?-Witness: In constitution. That is the distinction between water of constitution and water of solution. There are three conditions or states of arsenic acid :-There is the anhydrous, or acid absolutely free from water; there is the dry, which has a certain proportion of water, but in constitution or combination; and what we may call the wet, or acid held in solution. We can, and have used the acid in the second condition for the production of the two dyes; but it is more advantageous to use the solution with about one-third, or thirty per cent., of water. In this case, all the mechanical water comes off before the colour is produced; and it is, undoubtedly, the dry arsenic acid of commerce which operates on the aniline to produce the |