TECHNICAL CHEMISTRY.

On a Constant Aspirator and Blower,
by M. CAREY LEA, Philadelphia.

VARIOUS modes of producing a blast of air by means of the flow of water have been proposed for laboratory use. A somewhat complicated system, involving the use of two fluids, mercury and water, was published in the Philosophical Magazine some years ago, and more recently an application by Dr. Sprengel of the well-known principle of the Catalonian blast furnace was described. It occurred to me that this principle might be made use of for aspirating, as well as for driving a current of FIG. 1. air, and experiment fully confirmed the idea. I have also modified the shape of the arrangement for catching the air described by Dr. Sprengel, introducing the current of water horizontally instead of vertically. I shall first describe the instrument intended for aspirating, and next, the complete apparatus for all purposes.

The aspirator is extremely simple. It is nothing more than a tin tube, represented by Fig. 1, about two feet long, and four-tenths of an inch internal diameter, with a branch threetenths of an inch in diameter and four inches long, inserted horizontally at a distance of four inches from the upper end.

FIG. 2.

For use, the tube is supported vertically in any convenient manner over a sink. An India-rubber tnbe, communicating with a water faucet, is passed over the end of the small horizontal tube A. Another Indiarubber tube connects the opening B with the apparatus through which air is to be drawn. As soon as the current of water is established, the air is aspirated. In the figure subjoined, the air enters at D, after being aspirated through the Wolfe's bottle, or other apparatus through which it is desired to pass a current of air, enters the tin tube at B, and is drawn through with the water supplied by the pipe A, and escaping at c. The power of this instrument is such that, with one no larger than here described, a column of water of fifteen inches was easily displaced. The end c may be inserted into the funnel of a Liebig's condenser, and the water employed for cooling may be made at the same time to keep the aspirator in action.*

E

The aspirating tube (which may also at need replace the blowing tube subsequently to be described) FIG. 3. may be easily made by the manipulator himself. A stout cork is bored parallel to its axis and to one side of the centre (not in the middle, as in the figure), and then a smaller hole is made at right angles to the first, communicating with it, but not passing further. Three pieces of tube are then fitted into the cork, not allowing either to extend as far in as the junction. The cork is then brushed over with sealing wax dissolved in alcohol.

FIG. 4.

B

It is, however, a more convenient plan to construct an apparatus capable of combining both Such an the functions of blowing and aspirating. arrangement is exceedingly useful, and can be made with very little trouble. For this purpose, a tin pipe, A B, about three feet in length and half an inch internal diameter, has two smaller pipes, four to six inches long, soldered into it. These are three-tenths of an inch in internal diameter. One, C D, is inserted at right angles, about four inches from the end; the other is inserted about an inch lower, and makes an angle of about 45°. The lower end of the tube passes through the cork of a tolerably wide-mouthed gallon bottle, extending rather more than half way down. The tubes may be made of smaller calibre and shorter, even 18 inches answers very well; but the sizes given are those which I have found to afford the best results. The tin pipes can be made by any tinsmith in a few minutes.

Two glass tubes also pass through the cork† of the bottle, a short small tube, G, over the outer end of which an India-rubber tube is passed, and a large tube, H, about half an inch in

bore, extending to the bottom of the bottle. Its outer end bends over, and is connected by six inches of Indiarubber tube with a straight tube of equal diameter. This last arrangement forms the siphon.

When the apparatus is to drive a blast, an Indiarubber tube is connected with a hydrant and attached

The tube a should extend six or eight inches above the cork, and should not pass below it, as represented in the figure.

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to the open end of the short horizontal branch of the tin tube. When the water is turned on, the Indiarubber tube, G I, is closed for a moment with the finger and thumb. This starts the water through the siphon, and then a continuous and powerful blast of air is driven through the tube, G I, which may be attached to a blowpipe, a Herapath burner, or be used in any way desired. The main point is this, that the siphon must be capable of carrying off a larger stream of water than that which is allowed to enter. In this way there is never more than an inch or two of water in the bottle, and some air escapes through the siphon, but without stopping its play. Otherwise the bottle may fill up, and water be driven through G I. The proper balancing is easily attained, and then the apparatus may be put in motion or stopped in a moment, and when in motion goes on indefinitely.

When the apparatus is to be used as an aspirator, the tube I is closed by inserting a glass rod, or passing over it a Mohr's stop-cock. B is closed by a cork, and E is connected with the apparatus through which the current of air is to be drawn, or E may be closed and the connexion made with B.

The arrangement here described for introducing the air and the water at the upper part of the tube was ascertained, after a number of experiments, to be that which was most effective. When the water is thrown horizontally into the vertical tube, it appears to carry with it a larger volume of air than when introduced perpendicularly or in an inclined position. Although the force of the current of air may be regulated, to a considerable extent, by diminishing or increasing the stream of water, yet it is to be observed that there must be a certain proportion between the stream of water and the size of the tube. A large tube ceases almost abruptly to produce any air current when the stream of water is reduced below a certain point, and a small tube will not give an air current of more than a certain force, no matter how great the stream of water. If it is desired that a single apparatus shall produce all degrees of action, a tin tube, like that before described, but a little larger in all its parts, may be provided, with a cork fitting its upper extremity. Through a hole in this cork passes a thick glass rod, or tube sealed at one end, of the same length as the tin tube. The introduction of this cork and rod diminishes the effective calibre of the tube, and enables it to blow or aspirate a gentle current of air with a stream of water which would otherwise have failed to set the apparatus in motion; at the same time, it can easily be removed when a powerful air current is desired. The air in this case is derived wholly from the small inclined tube.

I have found this instrument to be of the greatest utility and convenience; so much so, that I have two of them permanently fitted up in my laboratory. One valuable application is for getting rid of poisonous vapours. In any distillation, for example, the recipient or Wolfe's bottle may be made to communicate with the open air or with a chimney, a cork with a tube may be inserted into the retort, or an extra tube through the cork of the flask in which the distillation is performed, and the flexible tube, G I, passed over it, and a current of air be driven through during the whole operation. Or, if the products of distillation are valuable, the tube may be closed at I by one of Mohr's stop-cocks during the distillation, and at the end a current of air may be passed through the apparatus, sweeping it perfectly clean. In this way I have been able to dissolve oxide of iridium containing osmic acid in aqua regia, and drive

(CHEMICAL NEWS, Jan. 24, 1863.

off the osmic acid without suffering any inconvenience from the latter. The chemist who has once used this arrangement will find it so simple and efficacious that he will be led to employ it when manipulating with substances much less deleterious than osmic acid. It is very convenient in operations where chlorine is to be passed over or through substances, especially where the operation requires to be occasionally interrupted to examine the result.

For driving a blow-pipe, an apparatus of this sort, put together with a bottle and a few pieces of tube, is infinitely more convenient than the most expensive and cumbrous table blow-pipe fed by a double bellows, especially when it is desired to ignite at high temperatures for a length of time, the automatic nature of the instrument removing the necessity for working the bellows. A considerable degree of heat is easily obtained. A silver piece was laid on a fragment of brick, and the flame of a Herapath burner, fed with a stream of air by this instrument, was turned down upon it: the coin withered up immediately. A similar coin was easily fused to a bright button in a porcelain crucible heated from below. Thick brass wire was melted off in drops, &c.

It is not necessary that the instrument should adjoin the blow-pipe or apparatus for which the air current is wanted. In one of mine, the current produced by the tube A B, two feet long, is carried through tubes about sixteen feet, and might easily be carried further without important loss of power.

The quantity of water required for keeping the apparatus in action depends, of course, upon the force of the current of air desired, but is never large. In an experimental trial, it was found that, with a consumption of water of 80 litres per hour, a stream of air amounting to 400 cubic centimètres per minute could be maintained; or, in other words, a cubic mètre (about a ton) of water would suffice to keep the apparatus in motion for twelve hours. This instrument may be appropriately called an Eolus.--American Journal of Science.

On Commercial Perchloride of Phosphorus,
by M. MULLER.

THIS compound has been for some time manufactured on the large scale, by saturating a solution of phosphorus in sulphide of carbon by dry chlorine. Some inconveniences attend this process, the worst being the liability of the product to become sulphurous,* and another, that it often contains free phosphorus, as is notably the case when the sulpho-carbonic solution is over concentrated, and cooled too suddenly at the beginning of the operation, before all the phosphorus has passed to the state of protochloride. In this case, a fawn-coloured and waxy product is obtained, clearly distinguished from pure pentachloride, which is yellow and crystalline.

If, after the operation, sulphide of carbon, forming the mother waters, is simply decanted, when cold the crystalline crust can be preserved intact for some time; but, after a certain time, it liquefies, and is reduced to protochloride of phosphorus. When much free phosphorus is present, this reduction can be effected suddenly, but then giving rise to dangerous projections.

of

To obviate these difficulties, M. Muller proposes, in

When cold, sulphide of carbon is only feebly attacked by chloride phosphorus, and it is only in the end that the product becomes sulphurous, but, with heat, the reaction is very sensible.

CHEMICAL NEWS,

Jan. 24, 1863.

PHARMACY, TOXICOLOGY, &c.

A Few Remarks about Extracts, by J. SCHWEITZER. EXTRACTS contain the soluble active portions of plants, and, in a few instances, of animals, as cantharides, castoreum, &c. They are principally administered in the form of pills, for which purpose they require a certain consistence. Recently, a new sort of extracts have made their appearance, which are not evaporated to a pilular consistence, but are simply reduced to a semi-fluid, syrupy condition, and are called "fluid extracts"; they constitute a different and perfectly separate class.

The solutions which yield the extracts are obtained by means of water, alcohol, or ether. The mode of obtaining these solutions varies with the nature of the substance operated upon, and requires similar manipulations to those used for making tinctures, infusions, or decoctions. We prepare extracts accordingly by

1. Crushing the fresh plant, and expressing the juice

or sap;

2. Macerating the substance in cold water; 3. Making an infusion or decoction; or, 4. Percolating the substance with water, alcohol, or ether.

Extracts prepared by evaporation of the expressed juice of fresh plants, may be taken as types of what solid extracts should be. They possess the active principles of the plant unaltered and in a concentrated form; the chlorophyll, the gummy and albuminous matter, renders them plastic and admirably adapted for the making of pills, and, when properly prepared, they keep soft and good for many years. Albumen in a moist state is one of the most unstable compounds known, and often proves a source of annoyance and loss to the pharmaceutist, so that it has been proposed to remove it altogether from the extract. But this can only be effected by removing, at the same time, all the other coagulable matters. The generally-considered inert and objectionable chlorophyll and albumen, however, cannot be separated without injury to the appearance of the extracts, whose therapeutical effect may also, at the same time, become slightly modified. But it has been found that albumen, when preserved in a perfectly soluble condition, does not decompose and spoil an extract containing it, and that the intermediate state, partly coagulated and partly soluble, is most liable to subsequent decomposition; we may, therefore, with advantage, retain these substances in our extracts. It is hardly necessary to add, that extracts quickly prepared and evaporated at a low temperature are, in every respect, preferable to those obtained by long-continued boiling.

The roots, stalks, leaves, or whatever parts of the fresh plant have to serve for making an extract, must be fresh, in proper season, and sound; they should be well cleaned from all adhering sand before they are crushed, a process which is best effected in a mill. When the

39

roots, &c., are of too dry a nature, the grinding or crushing can be accompanied by an addition of water sufficient to obtain from the pressed mass a volume of fluid equal to about three-quarters of the original pulp. This liquid has to be strained through cloth and quickly evaporated, to prevent incipient fermentation; the inspissation should proceed rapidly, but at a lower temperature than 2120. A long shallow pan, heated by warm water, may receive the strained juice, and the evaporation assisted by a current of air forced over the surface. When reduced to a pasty condition, it may be transferred to a water bath, and finished by constant stirring till it assumes the pilular consistence. In this way a firm plastic extract will be obtained which keeps well, and possesses the natural properties of the original plant in a concentrated and unchangeable condition.

In this manner almost all the extracts of fresh juicy plants may be prepared. The following are those more generally used:-Extracts of aconite, belladonna, colchicum, conium, cotyledon umbilicus, digitalis, hyoscyamus, lactuca, stramonium, taraxacum.

Extracts prepared by maceration in cold water are but few in number, extracts of aloes and liquorice juice being, perhaps, the only ones which require some comment; these are what may better be called purifications of previously prepared crude extract. The aloes and liquorice are broken into pieces the size of a walnut, and placed with straw in alternate layers, till they fill the vessel, which, for greater convenience, should have a contrivance by means of which the saturated liquor can be withdrawn without much disturbing the vessel itself. The top layer should be covered by a weight, to prevent the water from lifting and disturbing the contents. After the vessel has been filled with cold water, and allowed to macerate for twenty-four hours, the liquor should be withdrawn and replaced with fresh water, repeating this operation two or three times, till the ingredients are exhausted. The clear liquors may each time be evaporated, either on a steam or water bath, the products mixed, and brought to the proper consistence.

The most complex and important of all our drugs is opium, the extract of which is also prepared by maceration in cold water. The nature of opium rendered it, no doubt, a difficult task to devise a process of extraction which should fulfil all requirements; but the perfect chemical knowledge of all its component parts has expunged a number of most unnecessary, and sometimes absurd processes, which were occasionally followed. Simple and effective as the treatment of opium with cold water is, I do not think that the result is so perfect as to defy all improvement. We possess private preparations of opium (Liquor opii sedativus, for example) which stand in higher repute than any of the Pharmacopoeia opiates. The usual complaints against ordinary opium preparations are their variable strength and exciting properties, the first caused, no doubt, by differences in the drug itself, the other, perhaps, by a peculiar acrid, odorous principle.

The natural cause of the variable strength of opium are the different proportions of gummy, resinous, saccharine, and feculant matter which find their way into the watery solutions containing the active properties of the drug. We find that formerly many eminent pharmaceutists subjected the opium to fermentation, and used the fermented liquor for their preparations. Such processes were usually kept secret, and became only known after the lapse of years, and after the preparation had acquired some reputation. Fermentation undoubtedly removes many of the inert constituents of

Lord Chief Justice Cockburn: If you meant to express what we understand Dr. Medlock meant to express, namely, "dry," as contra-distinguished from acid in solution, you would call it "dry hydrate?"-Witness: I should call it "dry hydrate,” certainly.

By Mr. Day: In my experiments I have used arsenic acid in all states, from the anhydrous to the hydrated acid, containing 66 per cent. of water. I do not mean to say I have made experiments in every degree of hydration, but ranging between those points. The anhydrous gave absolutely no colour.

Lord Chief Justice Cockburn: I take it that we may assume this-supposing "dry" must necessarily be taken to mean "anhydrous," there is an end to the patent.

Sir F. Kelly: We quite agree with that on our side. We say that the article of commerce, known as "dry arsenic acid," will do.

Examination continued: If you took arsenic acid containing one, two, or three equivalents of water, hydrated arsenic acid would be the proper expression to use. "Dry hydrated bichloride of tin is a scientifically and strictly correct expression. The first experiment in which I got colour was made with 5 per cent. of water. I obtained but a small amount. Whether, commercially speaking, that would be a practical way of procuring the colour would depend entirely on the price given for it. There would be a waste of material. The greater part of the aniline would boil off, and most of what remained would be decomposed by the high temperature. I obtained the most successful result with 66 per cent. of water. The experiments were made in this way. I took equal weights of arsenic acid and aniline in each experiment. The arsenic acid was combined with a certain portion of water, and each was subjected to precisely the same process. The results increased in proportion up to 66 per cent. of water. One hundred parts of arsenic acid in the dry state, and eighty-one parts of aniline, were what I took. With 20 per cent. of water I obtained more colour than with 10 per cent., but less than with 66 per cent.

Lord Chief Justice Cockburn: Does that warrant the inference, that it would be better still if you increased the water further?-Witness: No: I take it that there are two objects in view in the use of water; one to effect the combination of the arsenic acid with the aniline, which would be impossible in the absence of water; and the next, to prevent the rising of the temperature. If you have aniline, you cannot boil it off below 360° F. The boiling point of the mixture with 66 per cent. of water would be much below that of aniline. Diminution of temperature prevents destruction of colour. I have bought arsenic acid of the gentlemen who are in the habit of supplying me with chemicals-Bolton and Barnitt. I ordered "dry arsenic acid," and got it practically anhydrous. I have only bought dry arsenic acid in small quantity for my laboratory experiments. I have never bought it as an article of commerce. I know it has been used by calicoprinters, but I am not familiar with it. [The witness exhibited specimens of wool dyed with the colour produced by various proportions of water.]

Cross-examined by Mr. Grove: My experiments were made at the works of the defendants, with acid made by them. For the anhydrous experiment, I took acid which I ascertained to be anhydrous. I took another, which had been boiled down till it contained 19 per cent.; another, boiled down till it contained 5 per cent.: for the larger proportions I diluted the acid. I made my experiments independent of any patent. The mixture was heated gradually, by means of an oil-bath, until colour was deve loped-when there was any colour. It was heated to 360°, at which temperature the aniline not combined with the arsenic acid would boil away. The aniline is not wasted; it is distilled off, and used again. If I sent for arsenic acid, it would depend on what I wanted it for, whether I should order hydrated arsenic acid. If I wanted simply arsenic

41

acid, I should simply order arsenic acid. Tartaric acid is a combination of two atoms of water and one of acid. It may be called a hydrate. In ordering tartaric acid, I should not order hydrated tartaric acid. In speaking of dry tartaric acid, I should not speak of the anhydrous acid; I should speak of the dry acid which contained water in combination. I do not know the exact date at which I ordered the arsenic acid of Bolton and Barnitt; it must have been twelve or fourteen months ago. I do not know in what sense the patentee may have used the word "dry," but I know I have always used it in the ordinary sense; that is, as practically free from moisture as you can get a thing. When you are told to use a dry thing, you make it as dry as you can.

By the Lord Chief Justice: Arsenic acid may combine with water without holding it. You may get crystals. There is no doubt there is a combination between arsenic acid and water.

The Lord Chief Justice: The question is, whether the term "dry" is satisfied by having water in combination, so long as it is not present in the shape of moisture appreciable to the senses?-Witness: I think you would have to strain a good deal for that. I do not think that is the fair and ordinary sense in which you would interpret it. With regard to metastannic acid, which I have said in my book, when dried in the air consists of SnO10 + 10 HO I have already stated that the term "dry must be taken correlatively. I do not use it in any strained sense-it depends on what it is associated with. Arsenic acid is a deliquescent substance, and if I am told to make it dry, I make it as dry as I can.

Lord Chief Justice Cockburn: When you speak of deliquescent, the water is visible, not in combination, but only mechanical?-Witness: It is mechanical; it takes up moisture from the atmosphere.

Lord Chief Justice Cockburn: Then, when you are speaking of a thing notoriously deliquescent, and you find that a person is speaking of it as dry, must not that be taken to mean the divesting it of water that would render it deliquescent?

Mr. Grove: It cannot possibly be divested of water so as to render it not deliquescent, because it would become deliquescent again.

Lord Chief Justice Cockburn: What I mean is, whether you may not take the term "dry" not as anhydrous, but as divested of all water except that in combination?— Witness: I can give a reason: I will simply state that this must be read in connexion with other processes, in a good many of which it must be absolutely dry.

Mr. Grove: In your description of metastannic acid you say that acid dried in the air consists of Sn,010 + 10 HO; when dried at 212° it loses half its water; and by ignition becomes anhydrous. You use the terms "dry" and "anhydrous" in contra-distinction.-Witness: They are relative degrees of hydration.

Mr. Grove: I believe a thing may be anhydrous and still not dry.-Witness: It may be liquid: bichloride of tin is a liquid free from water.

Mr. Grove: It is anhydrous, not dry.-Witness: It is anhydrous, not solid; that is the proper way of putting it. Anhydrous means free from water: it can have no other meaning than that.

Mr. Grove: In your book you say oxide of copper is made anhydrous by boiling it in water?-Witness: Yes.

Mr. Grove: You do not say you make it dry?-Witness: No: oxide of copper is not in combination with water. Any substance may be mixed in water; that does not affect its anhydrous condition.

Re-examined by Mr. Hindmarsh: Anhydrous tartaric acid is not sold.

Mr. Hindmarsh: What meaning would you attach to the term "arsenic acid" simply?-Witness: I think I should consider it in the solid state, not necessarily so. If the term "arsenic acid" were used generally, it would