NEWS

barton, where this same formation occurs, the lime- as a convenient means of regulating the pressure of the stones were found to contain no inconsiderable quantity stirrup. of sulphuric acid, and fissures are often found filled with

radiating crystals of gypsum.

I had intended examining in a similar manner some of the dolomitic limestones from the other localities where this formation is exposed, but I have been only able as yet partially to examine two varieties from the beds situated in the hills above Greenock. The strata are there inclined at a pretty high angle, but have a similar appearance to those in Ballagan Glen. I could not find here any gypsum, but there are abundant layers of white fibrous carbonate of lime, and which presents the same aspect, and occupies a similar position to the gypsum in Ballagan Glen.

The following table exhibits the proportions of insoluble, lime, and magnesia, in the two beds:

Continuous Filtration (FIG. 1).

These specimens are much purer than the others, and it would be interesting to find out what relative position they occupy, with regard to the strata in Ballagan Glen, seeing they are so far apart.

I do not think that we can explain the formation of these beds upon the supposition that they were originally limestone, and subsequently converted into dolomite. From their somewhat nodular structure, and impure character, it appears as if they had rather It is obvious that if t'e counterpoise on the centre proceeded from the segregation of a dolomitic mud, so to board is adjusted so that the weight of the filter when speak. At all events it is quite evident that the con- filled to the height desired will turn the scale, the version- if such was required-must have taken place pressure of the stirrup on the india-rubber tube will at, and not subsequent to, their deposition. The pres-immediately cut off the supply. In practice it is found ence of gypsum in the series does not support the idea that the magnesia may have originally existed as sulphate, the relative amount being so small.

DESCRIPTION OF AN

AUTOMATIC ARRANGEMENT

FOR

CONTINUOUS FILTRATION AND WASHING
PRECIPITATES.

BY HENRY B. BRADY.

[A WORKING model of the apparatus was exhibited at the Norwich meeting of the British Pharmaceutical Conference, and an extempore description was given, of which the following is a summary. As the arrangement requires modification for the two distinct operations for which it is designed, it will be necessary to give a separate description of the two forms. Woodcuts 1 and 2 illustrate the subject.]

The arrangement for continuous filtration is exceedingly simple. The object is to keep a filter constantly filled up to a certain height. The rigid stand, a, a, a, a, consisting of two horizontal boards connected by two uprights, may be replaced by any convenient laboratory fittings, its object being to carry a funnel-holder, b, which swings freely on a pivot, d. One arm holds the funnel, the other is balanced by a suitable weight, c. A vulcanised india-rubber tube, e, e, and a wire stirrup, f, are the only other essential portions of the arrangement. The stirrup encircles the flexible pipe, and, passing through the upper board, is connected with the arm which holds the funnel. A wire rack, g, is added

that the supply very soon adjusts itself exactly to the rate of filtration, and then the funnel remains stationary. The fluid may be supplied in many ways; a common washing-bottle answers very well, or a tap-jar may be employed, or any other similarly convenient appliance. The drawing shows a somewhat more complicated arrangement, in which the supply is brought from an open beaker by means of a syphon, in which case the suction-pipe must be kept closed by a pinchcock.

Dec., 1868.

Foreign Science.

Object, to provide an intermittent supply of fluid in such a way that the filter shall empty itself completely before it is filed again. The same rigid stand, and the sme oscillating funnel-board are used, but there is superadded another board like b, suspended in the same manner a little above it, as seen at h. This intermediate member holds a funnel, i, fitted with a Tantalus syphon, immediately above the funnel used for filtering, and has a wire and stirrup, k, working from the opposite end. Both stirrups being raised to commence the operation, the upper funnel is filled as high as the top of the Tantalus syphon, and therefore discharges itself into the filter. The filter, then, with the weight thrown upon it, turns the scale and cuts off the supply, just as in the simpler apparatus. It will be seen that if the stirrup, k, completely closed the elastic tube on the emptying of the upper funnel the operation would come to a standstill after the first delivery; and to avoid this a small screw, 1, is introduced to prevent the weighted end of the board swinging back to its full extent, so that when the filter is emptied and opens the tube at f, a slow stream commences to pour into the funnel, increasing in rapidity as the augmented weight raises the wire at k.

It is scarcely necessary to explain the principle of the Tantalus syphon-a contrivance familiar to many as the basis of a philosophical toy. It consists of a bent tube like a U, with one arm longer than the other. The longer arm is fitted into the tube of a funnel by means of an india-rubber washer. Its syphon action is brought into play directly the fluid in the funnel has risen above the level of the top of the bend, and it then draws off the contents as far as its shorter arm reaches. The figures will explain the rest.

The application of the principle to the large filters used for manufacturing purposes will naturally suggest itself, and though the model exhibited was made for analytical purposes on a small scale, there is no reason that modifications to suit any variety of circumstances should not be introduced.

The simpler form of apparatus is in regular use in one or two laboratories for filtering solutions. A multitude of cases occur to the pharmaceutist in which it is desirable that his filter should never run too low, as in the separation of essential oils from distilled waters, and in such as these its employment would be of great advantage.

The arrangement was designed by Mr. W. Rennoldson, of Newcastle, and the model shown was lent by Mr. A. Freire-Marreco, Reader in Chemistry in Durham University, who has since presented it to the Museum of the Pharmaceutical Society at Bloomsbury Square. Pharmaceutical Journal.

FOREIGN SCIENCE.

PARIS, OCT. 21ST, 1868.

Employment of Vegetable Tar in Dyeing-New Process for
Generating Chlorine.-A Thallium Detonating Mixture
Manufacture of Permanganate of Potash.-Pulverized Coke
in Piles of great Resistance.

M. LEFORT has published a note on the employment of vege-
table tar in dyeing. In the year 1851, M. Pettenkoffer observed
that wood vinegar exposed to the action of ammonia and of
perchloride of iron, became coloured a deep violet. M. Pauli,
his assistaut, endeavoured to isolate the substance which
caused this reaction, and obtained, by treating the acetic
acid from wood with sulphuric ether, an acid crystal-

327

lising in fine needles, very soluble in water, alcohol, and ether, presenting the characters of pyrogallic acid; subsequent examination, however, proved this body to be pyrocatechuic acid. The circumstances under which oxyphenic acid is produced, and the very deep colouration acquired by tar water upon the addition of a salt of sesquioxide of iron, led M. Lefort to think that vegetable tar might be useful have left no doubt as to its applicability. According to in dyeing textile matters. Experiments in this direction analyses made, vegetable tar contains on an average about in water, the more concentrated the solution, the more colI per cent of oxyphenic acid, and as this acid is very soluble oured the dye bath. Upon the addition of perchloride of iron, the tar water is immediately coloured a dirty green, which is changed to a violet tint by the addition of potash or ammonia; but, with or without the addition of alkali, the oxyphenate of iron formed under these circumstances fixes itself upon animal and vegetable fibres, to which it communicates an ash-grey colour of great solidity. To dye textile matters with oxyphenate of iron, the following is the method of operating:-The fibres are steeped in a solution of perchoride of iron for several hours, and, when sufficiently taining one of vegetable tar to ten of water, heated to 60° drained, transferred to a vessel of filtered tar water, conor 8o. After several hours' maceration, they are withmove the aromatic and resinous principles. Soap does not drawn, washed with water, and afterwards with soap to refibres, and the resulting impression presents all the solidity act upon the colouring principle which is fixed upon the common to pigments having iron for the basis.

A Belgian chemist has devised a new process for generating chlorine. He first forms trisulphate of sesquioxide of iron, by the direct combination of this oxide with sulphuric acid, and then mixes the trisulphate obtained with 3 equiva lents of chloride of sodium or other convenient chloride. Upon heating the mixture in dry air, the chloride of sodium yields all its chlorine.

tion, of 8 parts of teroxide of thallium and 1 part of protoM. Boettger has formed a mixture which inflames by fricsulphide of antimony.

Some facts worthy of attention, concerning the manufacture of permanganate of potash, have been pointed out by dilute solution of the manganate, a third of the manganic M. Stacdeler. In the preparation of this salt by heating a acid is reduced to the state of peroxide without taking part in the reaction; the case is the same when hydrochloric acid is used to effect the transformation, notwithstanding that this process permits of the use of concentrated solutions. Things happen differently when chlorine is employed. The following is a convenient method of operating:-The crude pulverised manganate is abandoned in its own weight is added, and a current of chlorine transmitted until the of water for several days, then a similar quantity of water liquid becomes red; the solution is frequently agitated, diluted with four times its volume of water, filtered through coarsely powdered glass, and reduced to one-fifth of its original volume. At this point the permanganate crystallises; it can be obtained in a state of purity by recrystallizations. The yield is co per cent of the weight of peroxide of manganese employed.

A note entitled "On the Part Played by Pulverised Coke in Piles of Great Interior Resistance," by M. Gaiffe, was amining the action of the pounded coke which is placed communicated at a recent meeting of the Academy. In exbeen led to conclude that this addition considerably auground the carbon in the piles of M. Leclanché, M. Gaiffe has ments the surface of the carbon element, and extends this surface to within a very minute distance of the porous veɛsel; it is probable that the employment of coke powder would give good results in all piles of great interior resistauce. The experiment was made with two batteries, the one sulphate of lead, the other sulphate of protoxide of mercury. Their interior resistance was much diminished, and their constancy became nearly perfect. The deviation

REPORTS OF SOCIETIES.

PHARMACEUTICAL SOCIETY.

THE opening meeting of the session was held on Wednesday evening, October 7th, under the presidency of G. W. Sandford, Esq. There was a very large attendance, and, for the first time, the meeting was honoured with the presence of a goodly number of ladies. We hope the council will in future invite ladies to their conversazione as well as to their opening meetings, for their presence always lends a charm to the proceedings, and has, we are sure, an influence for good on the students.

At no period of the history of this society has there been more cause for congratulation than the present. For twenty-eight years the council have laboured hard to promote the interests of pharmacy, and to render examination compulsory on those who shall carry on the business of a chemist and druggist. The attainment of this object by the Pharmacy Bill which passed both Houses of Parliament during the last session was, of course, a cause for rejoicing at this the first meeting of the society since the passing of the Act.

of a galvanometer with thick wire and not very sensitive, did not occupy. In speaking of systematic study, Mr. in permanent communication with the mercury battery, only Brady said it was in after life that the man who had done varied one degree in four and twenty hours; it was 28° at his elementary work well, systematically reaped its full adthe moment of closing the circuit, it was still 27° twenty-vantage; for he had ready a framework more or less elabofour hours later. rate in which each new truth finds a natural place. The amount of detail a student could impart to his work was, no doubt, partly dependent on the opportunities at his disposal and the bent of his mental powers, but its accuracy and usefulness depend on conditions entirely within his own command, and the first in importance was system, or regularity in the attendance of lectures, demonstrations, and laboratory practice. Each step in scientific knowledge is dependent upon the one that precedes it, and bears an equally close relation to that which follows. To miss a single lecture in a course consisting of a hundred seemed a trifling matter, but the real loss could not be measured by mere numerical proportion. It might easily happen that an acquaintance with a principle expounded in the neglected discourse is essential to the proper comprehension of many that follow. A German author, Richter, speaking of this sort of steady persistence in following out a well-devised course of educa tion, concluded a paragraph by saying that—" Regularity is unity, unity is God-like; only the Devil is changeable." The speaker then impressed upon the students the necessity of being thorough, not to be content with surface work, not to accept the appearance for the reality, the gilt for the gold. In learning a principle, they must strive to know the phenomena from which it has been deduced; in the acquirement of facts, they must seek to associate them with the laws by which they are explained. It could not be too often repeated that there is no royal road to knowledge; and the many tempting bye-ways that diverge from the straight course-green, sunny, and seductivethat promise to lead to the same goal, soon show, though winding and deceptive, and not easily traced, that to whatever end they do lead it is not the one desired. You may know them only by one fact-they always tend, just a little, downwards. The right road is up-hill-rough near its outset, and marred by obstacles that at a little distance look formidable. These are surmounted by toil and perseverance, but the achievement brings new spirit into the work, the bye-ways lose their fascination, and new difficulties are sought rather than avoided. The condition in which the drudgery of the onset becomes a labour of love is attainable by all; and until it is attained scientific progress is hard and uncertain. Mr. Brady then gave some useful advice on recreation, cultivating a taste for literature and general science, &c, and closed a most instructive and practical address by referring to the history of William Allen, F.R.S., the first president of the Pharmaceutical Society, whose youth gave him no special advantages, but who had to work his way to suc ceeding positions of increased responsibilities in that well-known pharmacy at Plough-court with which his name is inseparably connected, and who, by diligence, devotion, and earnestness, became the man of science whose memoirs on carbon, on carbonic acid, and on respiration, were amongst the finest researches of their daywho became the friend and associate of Davy, Wollaston, Berzelius, De Luc, and others of that noble fraternity of chemists and physicists,-the brilliant and fascinating lecturer on chemistry at Guy's Hospital and the Royal Institution,-and the philanthropist labouring hand in hand with Clarkson, Brougham, Wilberforce, and the rest of that devoted band, to whom civilisation owes the suppression of the slave trade, the amelioration of a barbarous penal code, and the initiatory steps in the spread of education.

The PRESIDENT called upon the professors to announce the results of their respective examinations at the close of the last session, and it was highly gratifying to hear them speak in such high terms of the conduct of the students. Whether in the lecture theatre, the botanical gardens, or the laboratory, they had not only conducted themselves well and gained the praise of those who had had an opportunity of watching their behaviour and comparing it with students at other schools, but they also went through their studies with real earnestness, determined to make the best use of their time, and to gain as much knowledge as they could. With regard to the prizes, medals, and certificates, they were never better merited than during the last session. The President then distributed the prizes, and called upon Mr. H. B. Brady, of Newcastle, to deliver an inaugural address. We congratulate the council on their choice of one so peculiarly fitted to open the session at such an important time as the present. The address is quite as applicable to students in our schools of chemistry as to pharmaceutical students, and we trust our short report may lead some to enter into their studies with renewed energy, bent upon searching into the mysteries of that branch of science to which they are giving their special attention.

MR. BRADY began by making a few observations on the present aspect of pharmacy in its social and ethical relations; they were no longer a mere voluntary association as they had been stigmatized in the House of Commons during the late debate, but now occupied the same relation to Government as other professional bodies who hold examining powers, the Legislature having, with general approval, given them, as a body, a certain monopoly on an educational basis, as it had done heretofore to lawyers, surgeons, and others; they had, however, with their new powers and improved position, new and increased responsibilities. Those who had given them new powers looked for an advantage in having a specially educated body of men to perform certain duties, and it was for them to qualify themselves for the enlarged sphere opened to them. No mere curriculum of college instruction could impart that sort of intellectual cultivation and tone of thought that places a man above the category of tradesmen, but they must quali fy themselves by closer mental training for that higher social position which it would be their own fault if they Hydrides of Hydrocarbons (Styrolenic series).— Volumetric

ACADEMY OF SCIENCES.
PARIS, OCT. 14TH, 1868.

Its formation in great quantity is characteristic of ethylbenzol, and distinguishes this from xylene or dimethylbenzol, the isomeric hydrocarbon. Although in smaller proportion, benzol is formed simultaneously with styrolene--prussiate. C12H1(C,H)=C12H ̧+C,H ̧. These are the most abundant, and to some extent the normal products of the decomposition of ethylbenzol; but, as the most organic reactions, secondary products are formed. Among the secondary products is toluine, or methylbenzol-C1HI, or C12H(CH). The proportion of this body formed in M. Berthelot's experiments amounted to about one-third that of the styrolene. Naphthaline, C.He, and hydride of naphthaline, C20H10, were also detected. The action of a red heat transforms then a small portion of ethylbenzol into dimethylbenzol by a sort of molecular transposition, which results from the metamorphosis of an ethylenic residue decomposed into two more stable methylenic residues,