NEWS

IN quantitative analyses there is, perhaps, no one part in the process on which more time is needlessly lost than at the balance. While a chemist should not consider any time lost which is needed for accuracy of results, yet he need not consume time attempting what is called accuracy of weighing far beyond the limit of error of the circumstances under which a balance in the laboratory, with the containing vessels of platinum, glass, and porcelain (used to contain the materials weighed) is placed. Some of our most accurate and distinguished analytical chemists, as Rose and others, we are informed, only weighed within I m.grm., using 1 to 2 grms. of the material; in my own practice, using from 0'500 to 1 grm., I consider it useless to weigh nearer thanm.grm. A little practice will soon enable any one to judge where to place the last m.grm. My remarks thus far apply to the great run of accurate chemical analyses. When it comes to the more precise study of atomic weights, I still adhere to the limit of m.grm., but increase the amount of material experimented with.

In regard to assay analyses of gold and silver, of course these rules are not meant to apply, for there we have a special balance whose beam is no larger than a wire, and whose entire range is very small, and therefore can be kept to an adjustment far exceeding anything that can be done with analytical balances of the most approved make.

Condensation of Air on the Surface of Platinum. In connection with the subject of weighing, I would add the following observations of mine on platinum vessels. After taking the weight of a clean platinum vessel, then wiping it thoroughly with a dry rag or soft paper, and replacing it on the pan of the balance, it will be found to have lost weight; if of the ordinary size used in quantitative analysis, it will be found to have lost 2 m.grms. or more. If allowed to remain on the balance for fifteen or twenty minutes, it will be found to have recovered its weight. This change has usually been attributed to moisture, but I have clearly established that this is not the case. The following is the result of some accurate experi

the surface, without using any violent friction. After being submitted to this operation it was replaced on the balance, and it was ascertained to have lost 2 m.grms., and after being allowed to remain for twenty minutes its original weight was restored.

The vessel was now transferred to a drying receiver over sulphuric acid, and allowed to remain six hours; placed on the balance, it weighed exactly what it did when placed in the drying receiver. It was now wiped as before, and on being replaced on the balance had lost 2 m.grms., which it recovered, as before, in fifteen or twenty minutes.

The vessel was now transferred to a receiver in which the air was saturated with moisture from wet paper, placed on the glass support. After six hours the capsule was placed in the balance, when it was found to weigh just the same as it did when it was introduced into the moist atmosphere. A dry atmosphere or a moist atmosphere was then shown to have no effect in producing this temporary loss of weight in the capsule.

From these experiments, it shows very clearly that there is air condensed on the surface of platinum that a little rubbing will remove; but it will soon return to the platinum after this treatment. The importance of this fact will be manifest to the analytical chemist, and make him cautious about taking the tare of his platinum vessels too soon after wiping them.

Gold-Lined Capsules and Crucibles.

While the analytical chemist cannot always indulge in every form of luxury of apparatus which might tend to facilitate and give precision to his researches, still they are very convenient and useful at times. Those who have had much to do with caustic potash and nitre heated to redness, know that silver vessels will not always answer their purpose. Under these circumstances gold vessels are very useful, but very expensive, and I have for some time been using what might be called a compromise vessel, made of platinum lined with gold; not platinum gilt, but made in the following manner :-A thick sheet of platinum is taken and the requisite amount of gold melted on the surface, the whole is then rolled out to the proper thickness for capsules and crucibles, and these latter vessels then made out of this sheet. There was some little difficulty attending the making of the first vessels, but this was entirely overcome in the establishment of Johnson, Matthey, and Co., Hatton Garden, London, where the vessels I use are made.

Weighing on Filters.

In weighing precipitates on the filter, the common method I employ is to take two filters of the size required, which have been cut to size together. These filters are placed on the balance and weighted one against the other. Ordinarily there will be but a few m.grms. difference in weight, which difference is marked in small numbers with pencil on the heavier. These filters are placed on the funnel side by side, the substance to be filtered is poured on one, and the filtrate from the first is poured on to the second filter, and so with the washings. When the filtration and washing are complete, the two filters are placed on the warm bath and dried; the weighing being conducted in the ordinary way, only the empty filter is placed on the balance as a tare to the other, and due allowance made for the excess of weight of one filter over the other in taking account of the weight of the substance. This has some advantages over the ordinary way with the filter, as there is no need of any special precaution of washing the filter prior to use in any way, or drying in a glass tube, and using any precaution against the hygroscopic moisture that is likely to be absorbed by the dry filter, for there is always a filter an each side of the scale subject to like conditions. It enables me at least to dispatch my work more readily and satisfactorily.

A Ready Method of showing the Absorption of Hydrogen by Palladium.

In the beautiful and important investigations of Graham upon the absorption of hydrogen by palladium, he described

56

CHEMICAL NEWS, February 5, 1875.

PROCEEDINGS OF SOCIETIES.

This same result I have been in the habit of exhibiting in my laboratory, with a small piece of very thin palladium, about 1 centimetres wide and 8 centimetres long. Light a small-sized Bunsen burner, hold the piece of palladium in the upper part of the flame; it will get red-hot, but remain in the same form as when introduced in the flame. Lower it now into the flame, until the unburnt gas from the centre of the flame strikes the bottom of the metal, when it will immediately coil upwards, and can be made to double on itself. Carry it back to the upper part of the flame and it will straighten itself again. There are some interesting chemical questions connected with this experiment that are worth working out, and at some leisure moment I will look into them; as, for instance, the absorption of the gas at this high temperature, and as to whether or not simply hydrogen is absorbed, the palladium thereby decomposing the hydrocarbon, &c.

THE PRODUCTION OF ANILINE COLOURS WITHOUT THE USE OF ARSENIC ACID.

It will be within the remembrance of readers of the CHEMICAL NEWs that Coupier, of Paris, was the first to succeed in producing fuchsine by the action, at a suitable temperature, of hydrochloric acid and iron in small quantities on pure aniline and nitrotoluol. Though Coupier's experiments were confirmed by Schützenberger, who showed the aniline-red obtained by Coupier's process to be identical with that usually manufactured, and found the yield somewhat greater than that obtained by the use of arsenic acid, the process was not applied industrially before 1872, when Meister Lucius, and Brüning, of Hoechst, Germany, succeeded in working it on a large scale. This firm, however, appear to manufacture their colours only in part by this method, as they still supply the market with dyes containing arsenic.

More recently, the Gesellschaft für Anilin Fabrikation, of Berlin, have erected new works, where no arsenic acid is used in the preparation of colours. Not only fuchsine (rubine), but all the colours derived from it which are manufactured by this company are warranted to be produced without the employment of arsenic, and to be entirely free from this poisonous reagent.

The Berlin Company are working Coupier's process with several important modifications, and produce from 200 to 300 kilogs. of fuchsine per diem. Some specimens of fuchsine and other colours manufactured by this Company appear to be products of unrivalled beauty, purity, and strength. The fuchsine is stated to be not only purer, but stronger than that made by the aid of arsenic acid, and is the pure hydrochlorate of rosaniline. The rosaniline base, from its great purity, is admirably adapted for the preparation of aniline blue, and is largely used by other manufacturers of aniline colours.

Being free from arsenic, these dyes are not only fitted for colouring sweetmeats, liqueurs, syrups, and pharmaceutical preparations of every description, but may be used in many other industrial purposes where poisonous colours would be more or less dangerous, as in the staining of paper, paper-hangings, toys, &c.

It is to be desired that other manufacturers of these dyes will adopt the new method, and relinquish the old arsenic acid process, which, apart from the inconveniences it has caused both manufacturers and consumers, has led to many lamentable accidents.

SOCIETY. Annual Meeting, 1874.

E. W. BINNEY, F.R.S., F.G.S., Vice-President, in the Chair.

THE Report of the Council was read, from which we extract the following:

Dr. Frederick Crace-Calvert, F.R.S., was born near London, on the 14th of November, 1819.

In the year 1835, when 16 years of age, he left London and went to France, where he commenced the study of Chemistry under the celebrated chemist Gerardin, at Rouen, and continued with him for two years. At the expiration of this time he went to Paris, and carried on his studies at the Jardin des Plantes, the Sorbonne, Collége de France, and Ecole de Médecine, his attention being principally given to the Natural Sciences.

About the age of 21 he was appointed to manage the well-known works of Messrs. Robiquet and Pelletici, where the manufacture of pure chemicals and pharmaceutical products is carried on. This position, however, he soon vacated, on being offered that of "Démonstrateur de Chimie Appliquée," under the eminent chemist Chevreul, and here he remained from 1841 till 1846, when he left France. From the former date his career as a

chemist began, and continued with untiring energy during the succeeding thirty-two years.

He published his first paper, "Sur l'Extraction de Quinine et Cinchonine," in September, 1841.

In 1843, in conjunction with M. Ferrand, he elaborated an interesting paper on the analysis of gases enclosed in some organs of plants, the gases being taken from the same plants at different times of the day and year, to demonstrate the action of the sun's rays. This paper is entitled "Memoire sur la Végétation, and may be found in vol. v. of the Comptes Rendus. In the following year the diseases of beer engaged his attention, and some interesting facts were embodied by him in a paper read to the Société de Pharmacie, "Sur la Fermentation visqueuse

de la Bière."

From 1843 till the time of his leaving France he was engaged in a research on some compounds of lead, which first brought him into note. One of the papers consequent on this may be found in the Comptes Rendus of 1843, entitled "Procédé au moyen duquel on obtient un Protoxyde de Plomb cristallisé at ayant la Couleur du

Minium."

In 1844 he wrote "On the Presence of Indigo in the Orchidaceous Plants;" in 1846, "On the Preparation of Calomel on the Large Scale;" and, in the same year, a compilation of facts relating to the properties of animalblack.

On returning to England, at the latter end of 1845, he was first appointed to the chair of the honorary professorship of chemistry at the Royal Institution, and afterwards to that of lecturer on chemistry at the School of Medicire in Pine Street, Manchester.

In 1847 he published a paper "On Bleaching Powders," and in 1848 one "On the Bleaching of Cotton and Flax." About this time Dr. Calvert gave a long series of lectures on his favourite subject, at the Athenæum, Manchester, "The Application of Chemistry to Manufactures." These were recorded in the daily papers.

During the following years many other subjects engaged his attention, but we may notice the following publications as some of the results of his labours:— In 1849, 66 Process for the Preparation of Chlorates, particularly the Chlorate of Potash."

In 1851, "On the Oxides and Nitrates of Lead."

58

PROCEEDINGS

OF THE

SOCIETY OF PUBLIC ANALYSTS.

In pursuance of an arrangement with the Editor of the CHEMICAL NEWS, a certain space in this Journal will henceforward be devoted to the interests of the above Society.

That the Public Analysts of the United Kingdom have formed an Association is probably pretty generally known already to the chemical world; but as this is our first appearance in a literary form it becomes us, in this place, to justify our existence.

With this view we propose to lay before our readers, as succinctly as may be, the history of our origin, and an explanation of the objects we have in view.

As long ago as 1860, the attention of Parliament was directed (mainly as the result of the extensive and valuable researches of Dr. Hassall and others) to the question of the adulteration of food, and a Bill for the repression of such adulteration-at that time very widely spread-was passed.

This Bill, however, from the defective machinery arranged for carrying out its object, was practically inoperative, and in 1872 the subject again called for and received the attention of the Legislature.

The Act of 1872-though a great improvement on the previous measure, and though it has admittedly been the means of checking, in a very great degree, the evil which it was its object to prevent-has not been successful to the extent that was hoped and expected. This has arisen from various causes, among which we may mention that the Bill was drawn by gentlemen who were but imperfectly acquainted with the subject; that it has been only very partially put into operation; that the number of chemists, alike able and willing to undertake the new duties required, was, at the time of its enactment, extremely limited; and that, from the loose wording of some of its clauses, the decisions of magistrates have frequently not been in accord one with another.

Besides this, it must be remembered that the tradesmen likely to be affected by an "Adulteration Act" form, in the aggregate, an enormous, wealthy, and influential body, and having, by a long immunity, acquired more or less lax ideas of what should be considered purity and what adulteration (though we do not mean to imply that they were less honest than their neighbours who were unaffected by the Act), they very naturally resented any interference with their "vested interests;" and "vested interests being in England uncommonly awkward things to meddle with, it is no matter for surprise that they obtained considerable sympathy from the general public, who, with wonderful unselfishness and self-abnegation, consented to swallow chicoried coffee, alumed bread, and watered milk, rather than that the grocer, the baker, or the milk-seller should be subjected to what appeared to them like oppression.

The complaints of the tradesmen, and the defects in the Bill itself, which daily became more apparent, at length led-as will be in the recollection of our readers-to the appointment, during the last Session of Parliament, of a Select Committee of the House of Commons, to enquire into the working of the Act, with a view to its amend ment. Mr. Clare Sewell Read, the Secretary of the Local Government Board, very ably presided over the deliberations of the Committee; and after numerous witnesses had been examined, the Committee issued a Report, which, together with the detailed evidence given before them, forms a Blue Book of more than 400 pages.

It is not our intention here either to animadvert upon the constitution of the Committee or to criticise any of the statements made before them. Suffice it to say that three things were made manifest:

First. That further legislation is probable, and this by itself pointed to the desirability of concerted action on the part of Public Analysts.

CHEMICAL NEWS, February 5, 1875.'

Second. That the representatives of each trade, though approving of the repression of adulteration in the abstract, held that their particular business should be exempted from the operation of any Adulteration Act, -so that if each section of trade was to be conciliated, no Adulteration Act whatever could be passed. Third. That, partly through ignorance and partly through prejudice, statements were made which the Public Analysts considered to reflect very unjustly on their ability and procedure.

It will thus, we think, be admitted that sufficient cause existed for the formation of our Society; and after a preliminary meeting of some half dozen Public Analysts, a general meeting of the whole body was convened by circular, and by notices in this and in other scientific journals, and was held on August 7th at the Cannon Street Hotel. This meeting was very numerously attended, the subjects which called it together were fully discussed, and a number of resolutions-embodying the collective opinions of the gentlemen present-were passed.

It was decided that a "Society of Public Analysts" be formed, and a Committee was appointed to undertake the initial work connected with its formation, and to draw up a definition of "an adulterated article " (which definition we print in another column). After a number of conferences the Committee completed their allotted task, and laid the results before a general meeting, held on the Ist of December last. At this meeting a Report, submitted by the Committee, was adopted, the definition-with some slight alterations-was accepted, and a Council of the Society was elected by ballot.

As we purpose on a future occasion to recur to the subject of the definition, we will only remark here thatthough it appears very simple, and might be thought to have involved but little trouble in its drawing up-the work really was an onerous one, and it was only after many conferences, and after obtaining the best assistance available, both legal and chemical, that the definition was finally drafted. It is perhaps needless to say more. It will be understood that we shall carefully watch the introduction of the Bill promised in the coming Session, willingly supply any information we possess, and generally-as far as we may have the opportunity-"educate" our legislators on a question to which, up to now, it would be only affectation to assume that they have devoted much

attention.

We have thus far only spoken of the immediate and temporary objects of the Society, but in its wider scope it will seek to embrace a mutual interchange of opinion amongst its members, a nearer uniformity of processes and results, a wider dissemination of new researches, and in every way to raise the standard of analytical work, more especially as bearing on the analysis of articles of food and drink.

Having thus, we hope, clearly defined our objects, it is, we trust, unnecessary to say that this Society does not wish to put itself in any way or degree in competition with, or to endeavour to rival, the Chemical Society, to which most of our members also belong.

As by the constitution of "The Society of Public Analysts" all analytical chemists, but no others, are eligible for membership, it is evident that our work, as compared with that of the Chemical Society, is very circumscribed, as we travel in a smaller circle, confining our attention to practical analyses, and leaving the more ambitious field of theoretical and speculative research to the older Society.