Chapter 7

By the action of caustic potassa, the reds are divided into four groups: 1, those which turn to a violet or blue; 2, those which turn brown; 3, those which are changed to a light yellow or gray; 4, those which undergo little or no change.

The first group comprises madder, cochineal, orchil, alkanet, and murexide. Madder reds are turned to an orange by hydrochloric acid, while the three next are not notably affected. Cochineal is turned by the potassa to a violet-red, orchil to a violet-blue, and alkanet to a decided blue. Lac-dye presents the same reactions as cochineal, but has less brightness. Ammoniacal cochineal and carmine may likewise be distinguished by the tone of the reds obtained.

A characteristic of madder reds is that, after having been turned yellow by hydrochloric acid, they are rendered violet on treatment with milk of lime. A boiling soap-lye restores the original red, though somewhat paler. Artificial alizarine gives the same reaction. Turkey-reds, however, are quite unaffected by acid. Garancine and garanceux reds, if treated first with hydrochloric acid and then with milk of lime, turn to a dull blue.

Madder dyes are sometimes slow in being turned to a violet by potassa, and this shade when produced is often brownish. They might thus be confounded with the dyes of the fourth group, i.e., rosolic acid, coralline, eosine, and coccine. None of these colors gives the characteristic reaction with milk of lime and boiling soap-lye. If plunged in milk of lime, they resume their rose or orange shades, while the madder colors become violet. Murexide is turned, by potassa, gray in its light shades and violet in its dark ones. It might, then, be confounded with orchil, but it is decolorized by hydrochloric acid, which leaves orchil a red. Moreover, it is turned greenish by stannous chloride.

A special character of this dye (murexide) is the presence of mercury, the salts of which serve as mordants for fixing it, and may be detected by the ordinary reagents.

The second group comprises merely sandal wood or sanders red, which turns to a brown. On boiling it with copperas it becomes violet, while on boiling with potassium dichromate it changes to a yellowish brown.

The third group includes safflower, magenta, and murexide (light shades). If the action of the potassa is prolonged the (soft) red woods enter into this group. Safflower turns yellow by the action of potassa, and the original rose shade is not restored by washing with water. Hydrochloric acid turns it immediately yellow. Citric acid has no action. Magenta is completely decolorized by potassa, but a prolonged washing in water reproduces the original shade. This reaction is common to many aniline colors. These decolorations and recolorations are easily produced in dark shades, while in very light shades they are less easily observed, because there is always a certain loss of color. Stannous chloride turns magenta reds to a violet. Hydrochloric acid renders them yellowish brown (afterward greenish?). Water restores the purple red shade.

The fourth group comprises saffranine, azo-dinaphthyldiamine, rosolic acid, coralline, pure eosine and cosine modified by a salt of lead, coccina, artificial ponceau, and red-wood.

Saffranine is detected by the action of hydrochloric acid, which turns it to a beautiful blue; the red color is restored by washing in water. Azo-dinaphthyl diamine is recognized by its peculiar orange cast, and is turned by hydrochloric acid to a dull, dirty violet. Rosolic acid and coralline, as well as eosine, are turned by hydrochloric acid to an orange-yellow: the two former are distinguished from eosine by their shade, which inclines to a yellow. Potassa turns rosolic acid and coralline from an orange-red to a bright red, while it produces no change in eosine. If the action of potassa is prolonged, modified eosine is blackened in consequence of the decomposition of the wool, the sulphur of which forms lead sulphide. Coccine becomes of a light lemon-yellow on treatment with hydrochloric acid. Washing with water restores the original shade. It affords the same reactions as eosine, but its tone is more inclined to an orange.

Artificial ponceau does not undergo any change on treatment with hydrochloric acid, and resists potash. Red wood shades are turned toward a gooseberry-red by hydrochloric acid, especially if strong. This last reaction not being very distinct, red-wood shades might be mistaken for those of artificial ponceau but for the superior brightness of the latter. If the action of potassa is prolonged, the red-wood shades are decolorized, and a washing with water then bleaches the tissue. Rocelline affords the same reactions as artificial ponceau, but if steeped in a concentrated solution of stannous chloride it is in time completely discharged, which is not the case with artificial ponceau.

VIOLET COLORS.

Violets are divided into two groups: those affected by potassa, and those upon which it has no action. The first group embraces logwood, orchil, alkanet, and aniline violets, including under the latter term Perkin's violet, (probably the original "mauve"), dahlia, Parme or magenta violet, methyl, and Hofmann's violets. The action of potassa gives indications for each of these violets. Logwood violet is browned; that of orchil, if slightly reddish, is turned to a blue-violet; that of alkanet is modified to a fine blue. Lastly, Perkin's mauve, dahlia, and methyl violet become of a grayish brown, which may be re-converted into a fine violet by washing in abundance of water. When the shades are very heavy, this grayish brown is almost of a violet-brown, so that the violets might seem to be unaltered.

The action of hydrochloric acid distinguishes these colors better still if the aid of ammonia is called in for two cases.

The acid turns logwood violet to a fine red, and equally reddens orchil violet. But the two colors cannot be confounded, first, because the two violet shades are very distinct, that of orchil being much the brighter; and secondly, because ammonia has no action on logwood violet, while it turns orchil violet, if at all reddish, to a blue shade. Hydrochloric acid, whether dilute or concentrated, is without action on alkanet violet. If the acid is dilute, it is equally without action on Perkin's violet and dahlia. If it is strong, it turns them blue, and even green if in excess. Hofmann's violet turns green even with dilute acid, but prolonged washing restores the original violet shade. Dahlia gives a more blue shade than Perkin's mauve. The action of acid is equally characteristic for methyl violet. It becomes green, then yellow. Washing in water re-converts it first to a green, and then to a violet.

The second group includes madder violet, cochineal violet, and the compound violet of cochineal and extract of indigo. These three dyes are thus distinguished: Hydrochloric acid turns the madder violet-orange, slightly brownish, or a light brown, and it affords the characteristic reaction of the madder colors described above under reds. Cochineal violets are reddened. Sometimes they are decolorized, and become finally yellow, but do not pass through a brown stage.

The compound violet of cochineal and extract of indigo presents this characteristic reaction, that if boiled with very weak solution of sodium carbonate the liquid becomes blue, rather greenish, while the cloth becomes a vinous-red--_Moniteur Scientifique.--Chem. News._

* * * * *

CHEVALET'S CONDENSO-PURIFIER FOR GAS.

The condenso-purifier shown in the accompanying cut operates as follows: Water is caused to flow over a metallic plate perforated with innumerable holes of from one to three millimeters in diameter, and then, under this disk, which is exactly horizontal, a current of gas is introduced. Under these circumstances the liquid does not traverse the holes in the plate, but is supported by the gas coming in an opposite direction. Provided that the gas has sufficient pressure, it bubbles up through the water and becomes so much the more divided in proportion as the holes are smaller and more numerous.

The gas is washed by traversing the liquid, and freed from the tar and coal-dust carried along with it; while, at the same time, the ammonia that it contains dissolves in the water, and this, too, so much the better the colder the latter is. This apparatus, then, permits of obtaining two results: a mechanical one, consisting in the stoppage of the solid matters, and a chemical one, consisting in the stoppage of the soluble portions, such as ammonia, sulphureted hydrogen, and carbonic acid.

The condenso-purifier consists of three perforated diaphragms, placed one over the other in rectilinear cast-iron boxes. These diaphragms are movable, and slide on projections running round the interior of the boxes. In each of the latter there is an overflow pipe, g, that runs to the box or compartment below, and an unperforated plate, f, that slides over the diaphragm so as to cover or uncover as many of the holes as may be necessary. A stream of common water runs in through the funnel, e, over the upper diaphragm, while the gas enters the apparatus through the pipe, a, and afterward takes the direction shown by the arrows. Reaching the level of the overflow, the water escapes, fills the lower compartment, covers the middle diaphragm, then passes through the second overflow-pipe to cover the lower diaphragm, next runs through the overflow-pipe of the third diaphragm on to the bottom of the purifier, and lastly makes its exit, through a siphon. A pressure gauge, having an inlet for the gas above and below, serves for regulating the pressure absorbed for each diaphragm, and which should vary between 0.01 and 0.012 of a meter.

The effect of this purifier is visible when the operation is performed with an apparatus made externally of glass. The gas is observed to enter in the form of smoke under the first diaphragm, and the water to become discolored and tarry. When the gas traverses the second diaphragm, it is observed to issue from the water entirely colorless, while the latter becomes slightly discolored, and finally, when it traverses the third diaphragm, the water is left perfectly limpid.

Two diaphragms have been found sufficient to completely remove the solid particles carried along by the gas, the third producing only a chemical effect.

This apparatus may replace two of the systems employed in gas works: (1) mechanical condensers, such as the systems of Pelouze & Audouin, and of Servier; and (2) scrubbers of different kinds and coke columns. Nevertheless, it is well to retain the last named, if the gas works have them, but to modify their work.

This purifier should always be placed directly after the condensers, and is to be supplied with a stream of pure water at the rate of 50 liters of water per 1,000 cubic meters of gas. Such water passes only once into the purifier, and issues therefrom sufficiently rich in ammonia to be treated.

If there are coke columns in the works, they are placed after the purifier, filled with wood shavings or well washed gravel, and then supplied with pure cold water in the proportion stated above. The water that flows from the columns passes afterward into the condenso-purifier, where it becomes charged with ammonia, and removes from the gas the tar that the latter has carried along, and then makes its exit and goes to the decanting cistern.

In operating thus, all the remaining ammonia that might have escaped the condenso-purifier is removed, and the result is obtained without pumps or motor, with apparatus that costs but little and does not occupy much space. The advantages that are derived from this, as regards sulphate of ammonia, are important; for, on treating ammoniacal waters with condensers, scarcely more than four to five kilogrammes of the sulphate are obtained per ton of coal distilled, while by washing the gas perfectly with the small quantity of water indicated, four to five kilogrammes more can be got per 1,000 kilogrammes of coal, or a total of eight to ten kilogrammes per ton.

When the gas is not washed sufficiently, almost all of the ammonia condenses in the purifying material.

The pressure absorbed by the condenso purifier is from ten to twelve millimeters per washing-diaphragm. In works that are not provided with an extractor, two diaphragms, or even a single one, are employed when it is desired simply to catch the tar.

The apparatus under consideration was employed in the St. Quentin gas works during the winter of 1881-1882, without giving rise to any obstruction; and, besides, it was found that by its use there might be avoided all choking up of the pipes at the works and the city mains through naphthaline.

In cases of obstruction, it is very easy to take out the perforated diaphragms; this being done by removing the bolts from the piece that holds the register, f, and then removing the diaphragm and putting in another. This operation takes about ten minutes. The advantages of such a mounting of the diaphragms is that it allows the gas manufacturer to employ (and easily change) the number of perforations that he finds best suited to his needs.

These apparatus are constructed for productions of from 1,000 to 100,000 cubic meters of gas per twenty four hours. They have been applied advantageously in the washing of smoke from potassa furnaces, in order to collect the ammonia that escapes from the chimneys. In one of such applications, the quantity of gas and steam washed reached a million cubic meters per twenty-four hours.--_Revue Industrielle._

* * * * *

ARTIFICIAL IVORY.

It is said that artificial ivory of a pure white color and very durable has been manufactured by dissolving shellac in ammonia, mixing the solution with oxide of zinc, driving off ammonia by heating, powdering, and strongly compressing in moulds.

* * * * *

CREOSOTE IMPURITIES.

[Footnote: Read at the meeting of the American Pharmaceutical Association held at Niagara Falls. 1882.]

By Prof. P. W. BEDFORD.

The object of this query can be but one, namely, to inquire whether the wood creosote offered for sale is a pure article, or not; and if not, what is the impurity present?

The relative commercial value of the articles sold as coal tar creosote and wood creosote disposes of the question as to the latter being present in the former article, and we are quite certain that the cheap variety is nothing more or less than a phenol or carbolic acid. Wood creosote, it has been frequently stated, is adulterated with coal tar creosote, or phenol. The object of my experiments has been to prove the identity of wood creosote and its freedom from phenol. The following tests are laid down in various works as conclusive evidence of its purity, and each has been fully tried with the several samples of wood creosote to prove their identity and purity, and also with phenol, sold as commercial creosote or coal tar creosote, and for comparison with mixtures of the two, that even small percentages of admixture might be identified, should such exist in the wood creosote of the market.

The following tests were used:

1. Equal volumes of anhydrous glycerine and wood creosote make a turbid mixture, separating on standing. _Phenol dissolves_. If three volumes of water be added, the separation of the wood creosote is immediate. _Phenol remains in permanent solution_.

2. One volume of wood creosote added to two volumes of glycerine; the former is not dissolved, but separates on standing. _Phenol dissolves_.

3. Three parts of a mixture containing 75 per cent, of glycerine and 25 of water to 1 part of wood creosote show no increase of volume of glycerine, and wood creosote separates. _Phenol dissolves, and forms a clear mixture_. Were any phenol present in the wood creosote, the increase in the volume of the glycerine solution, if in a graduated tube, would distinctly indicate the percentage of phenol present.

4. Solubility in benzine. Wood creosote entirely soluble. _Phenol is insoluble_.

5. A 1 per cent, solution of wood creosote. Take of this 10 cubic centimeters, add 1 drop of a test solution of ferric chloride; an evanescent blue color is formed, passing quickly into a red color. _Phenol gives a permanent blue color_.

6. Collodion or albumen with an equal bulk of wood creosote makes a perfect mixture without coagulation. _Phenol at once coagulates into a more or less firm mass or clot_.

7. Bromine solution with wood creosote gives a reddish brown precipitate. _Phenol gives a white precipitate_.

All tests enumerated above were repeatedly tried with four samples of wood creosote sold as such; one a sample of Morson's, one of Merck's, one evidently of German origin, but bearing the label and capsule of an American manufacturer, and one of unknown origin, but sold as beech-wood creosote (German), and each proved to be _pure wood creosote_.

Two samples of commercial creosote which, from the low cost, were known to be of coal tar origin gave the negative tests, showing that they were phenol.

Corroborative experiments were made by mixing 10 to 20 per cent, of phenol with samples of the beechwood creosote, but in every case each of the tests named showed the presence of the phenol.

The writer on other occasions applied single tests (the collodion test) to samples of beechwood creosote that he had an opportunity of procuring small specimens of, and satisfied himself that they were pure. The conclusion is that the wood creosote of the market of the present time is in abundant supply, is of unexceptionable quality, and reasonable in price, so that there is no excuse for the substitution of the phenol commonly sold for it. When it is directed for use for internal administration (the medicinal effect being entirely dissimilar), wood creosote only should be dispensed.

The general sales of creosote by the pharmacist are in small quantities as a toothache remedy, and phenol has the power of coagulating albumen, which effectually relieves the suffering. Wood creosote does not coagulate albumen, and is, therefore, not as serviceable. This is, perhaps, the reason that it has become, in a great measure, supplanted in general sale by the coal tar creosote, to say nothing of the argument of a lower cost.

* * * * *

REMEDY FOR SICK HEADACHE.

Surgeon Major Roehring, of Amberg, reports, in No. 32 of the _Allg. Med. Centr. Zeit_., April 22, 1882, a case of headache of long standing, which he cured by salicylate of sodium, which confirms the observations of Dr. Oehlschlager, of Dantzig, who first contended that we possessed in salicylic acid one of the most reliable remedies for neuralgia. This cannot astonish us if we remember that the action of salicylic acid is, in more than one respect, and especially in its influence on the nervous centers, analogous to quinine.

While out with the troops on maneuver, Dr. Roehring was called to visit the sixteen-year old son of a poor peasant family in a neighboring village. The boy, who gave all evidences of living under bad hygienic surroundings, but who had shown himself very diligent at school, had been suffering, from his sixth year, several days every week from the most intense headache, which had not been relieved by any of the many remedies tried for this purpose. A careful examination did not reveal any organic lesion or any cause for the pain, which seemed to be neuralgic in character, a purely nervous headache. Roehring had just been reading the observations of Oehlschlager, and knowing, from the names of the physicians who had been already attending the poor boy, that all the common remedies for neuralgia had been given a fair trial, thought this a good opportunity to test the virtue of salicylate of sodium. He gave the boy, who, in consequence of the severity of the pain, was not able to leave his bed, ten grains of the remedy every three hours, and was surprised to see the patient next day in his tent and with smiling face. The boy admitted that he for years had not been feeling so well as he did then. The remedy was continued, but in less frequent doses, for a few days longer; the headache did not return. Several months later Dr. Roehring wrote to the school-teacher of the boy, and was informed that the latter had, during all this time, been totally free of his former pain, that he was much brighter than formerly, and evidently enjoying the best of health.

It may be worth while to give the remedy a more extensive trial, and the more so as we are only too often at a loss what to do in stubborn cases of so-called nervous headache.--_The Medical and Surgical Reporter_.

* * * * *

SUNLIGHT AND SKYLIGHT AT HIGH ALTITUDES.

At the Southampton meeting of the British Association, Captain Abney read a paper in which he called attention to the fact that photographs taken at high altitudes show skies that are nearly black by comparison with bright objects projected against them, and he went on to show that the higher above the sea level the observer went, the darker the sky really is and the fainter the spectrum. In fact, the latter shows but little more than a band in the violet and ultraviolet at a height of 8,500 feet, while at sea-level it shows nearly the whole photographic spectrum. The only reason of this must be particles of some reflecting matter from which sunlight is reflected. The author refers this to watery stuff, of which nine-tenths is left behind at the altitude at which be worked. He then showed that the brightness of the ultra-violet of direct sunlight increased enormously the higher the observer went, but only to a certain point, for the spectrum suddenly terminated about 2,940 wave-length. This abrupt absorption was due to extra-atmospheric causes and perhaps to space. The increase in brightness of the ultra-violet was such that the usually invisible rays, L, M, N, could be distinctly seen, showing that the visibility of these rays depended on the intensity of the radiation. The red and ultra-red part of the spectrum was also considered. He showed that the absorption lines were present in undiminished force and number at this high altitude, thus placing their origin to extra-atmospheric causes. The absorption from atmospheric causes of radiant enemy in these parts he showed was due to "water-stuff," which he hesitated to call aqueous vapor, since the banded spectrum of water was present, and not lines. The B and A line he also stated could not be claimed as telluric lines, much less as due to aqueous vapor, but must originate between the sun and our atmosphere. The author finally confirmed the presence of benzine and ethyl in the same region. He had found their presence indicated in the spectrum at sea-level, and found their absorption lines with undiminished intensity at 8,500 feet. Thus, without much doubt, hydrocarbons must exist between our atmosphere and the sun, and, it may be, in space.

Prof. Langley, following Capt. Abney, observed: The very remarkable paper just read by Captain Abney has already brought information upon some points which the one I am about, by the courtesy of the Association, to present, leaves in doubt. It will be understood then that the references here are to his published memoirs only, and not to what we have just heard.