GRULET'S SCREW FOR RAISING WATER.

The French Agricultural Machínery Company has recently made a very interesting application of the screw for raising water for submersion and irrigation, and, to our knowledge, it is the first of its kind.

It is only necessary to examine the accompanying cut and observe the dimensions of the machine (which was constructed according to plans of Mr. Grulet) to recognize the fact that we have here a really practical application.

The screw, which constitutes the principal peculiarity of the system, has six blades, with a pitch of 0.465 m. On making 210 revolutions per minute it is capable of raising about 435 liters (95 gallons) per second to a height of 1.2 m (about 4 feet). The shaft that drives it revolves in a bearing which is bolted to a cross piece that is affixed to the cylindrical chamber. This latter consists of a cast iron case that is easily taken apart, and of a strong cylinder of iron plate whose upper extremity is connected, by means of riveted angle iron, with the bottom of the sluice. In the interior of the cylinder there are two cones, whose bases embrace the hub of the screw in such a way as to obtain a continuous superposition of the layers of liquid, and prevent bodies in suspension from penetrating between the rubbing surfaces of the bearing. One of the cones is made of iron plate, and is connected with the principal cylinder by four radiating braces and small angle irons, and the other is cast in a single piece with the box of the pivot.

The rotary axis is guided above by two pillow blocks held by the cross pieces of a frame that is riveted to the sides of the sluice. Finally, this latter terminates in a hinged gate which regulates the flow of the water.

Two beams that rest upon the sides of a stream will suffice in most cases to support the entire affair.

The mechanical duty of the apparatus is estimated at about 65 per cent. In the apparatus put up by Mr. Grulet, the motive power is furnished by a portable 10 H.P. engine. The boiler is a return flame one, with movable fire place, and the steam cylinder has a diameter of 0.2 m. (8 inches) for a piston stroke of 0.3 m. (about 12 inches). Before the apparatus was finally put in place it was sent to the last exhibition at Carcassonne, where it attracted very much attention from visitors. Its great regularity in working was particularly remarked. This quality, and the simplicity of its construction and the ease with which it may be put in place, are valuable features in apparatus that are designed to be looked after by inexperienced persons, and to operate in open air far from repair shops.—Revue Industrielle.

GRULET'S SCREW FOR RAISING WATER.

ON VARIOUS TONING BATHS.[11]
By W. M. Ashman.

In alkaline toning with borax or acetate of soda, the first consideration is to free the paper as much as possible from the excess of silver nitrate remaining therein over and above the quantity used in the production of the print; this is termed washing away the free silver. That operation is satisfactorily performed by soaking the prints in a few changes of clean soft water, usually four, or until the water is no longer opalescent when tested with a few grains of salt. The washing water so obtained is collected in the manner described to you by Mr. F. W. Hart, and precipitated with dilute hydrochloric acid. The vessel employed should be scrupulously clean, either earthenware, porcelain, or wood answering the purpose.

Experiment 1.—The treatment of the prints is sometimes followed by passing them into a dilute solution of sodium acetate or ordinary common salt, about one per cent., such as here shown, and stirring them about for five minutes, when it will be seen they have assumed a brick-red color, the object of which is threefold: First, the fibers become charged with a substance which acts as a chlorine absorbent, a necessary property to be mentioned further on. Secondly, a definite color is insured to start with, thus obviating the possibility of mistaking fresh prints in the toning bath for those which have become purple by reason of the deposited gold, an important consideration when dealing with fumed paper. Thirdly, the last trace of free nitrate of silver is removed, thereby preventing a too rapid decomposition of the toning bath.

Theoretically considered, it is proper that the last trace of silver nitrate should be removed; but those who are engaged in the daily practice of commercial work do not insist upon the strict observance of such a rule in all cases. An especial exception is permitted and advocated when dealing with prints from weak or underexposed negatives, this class being found to yield richer tones by not washing any of the free silver out.

The plan of soaking prints in a solution of sodium acetate was originally recommended, in lieu of washing, by a member of this Association, Mr. A. L. Henderson, as long ago as 1861, the following being an outline of the method suggested by him: Slightly overprinted proofs were soaked in a bath composed of

Sodium acetate240grains.
Water10ounces.

The unwashed proofs were moved about in this solution at least ten minutes, in order to convert all the free silver nitrate into acetate of silver. After slight rinsing in clean water the proofs were toned with

Gold terchloride4grains.
Sodium acetate240"
Water10ounces.

Among the advantages claimed was an entire absence from mealiness, a defect, you will remember, we now avoid by the adoption of ammoniacal fuming.

Guide-books to the practice of printing usually recommended three rapid washings; the decomposing action thus set up by the quantity of free silver remaining in the paper materially quickens the speed of toning. To prevent a too rapid deposition of gold some printers prefer adding a small quantity of common salt to the toning bath, which turns the prints sufficiently red and acts in some respects equal to an intermediary bath.

Preserved papers—containing, as they generally do, a certain proportion of free acid—are liable to give some trouble in toning, owing to the retarding action of the acid present. When this occurs, it is in a great measure overcome by the use of an intermediate bath of an alkaline character and sufficient strength to neutralize the acid. Either the carbonates of ammonia or soda are found useful for this purpose, and I cannot do better than quote the one mentioned by Mr. Frederick York, which, it will be remembered, is composed of

Washing soda1ounce.
Water1gallon.

Prints treated in the manner described are ready for toning by the alkaline method to be dealt with later on.

This brings us to the consideration of toning baths generally. The properties of toning baths vary somewhat according to the mode of preparation. The term "toning," as we understand it, implies a certain change of color brought about by chemical means, such as the deposition of a stable metal upon one that is easily affected by the atmosphere—electrolysis, in fact.

Evidently Mr. W. H. Fox Talbot was the first to use the toning bath in connection with paper photography, although he does not seem to have made much headway with his process at first; for it is recorded that from January, 1839, the date when Mr. Talbot communicated his discovery to the Royal Society, until 1845 very little improvement took place. These early paper pictures, be it remembered, were designated "photogenic drawings." Talbotype was not patented for some time afterward.

In the year 1845, however, it was found that steeping the paper in terchloride of gold vastly improved the results. It was not until 1853 that albumen took any part in the production of prints, the honor of its introduction being ascribed to Mr. Henry Pollock, although it seems that M. Le Gray, of Paris, about that time was producing stereoscopic pictures on albumenized paper. To M. Le Gray is due the credit of introducing gold toning in lieu of sulphur. The first toning then was performed by the decomposition of hypo., and known as "sulphur toning," by which fine black tones were obtained upon the addition of an acid, such as acetic, sulphuric, or other suitable oxidizing substance to the hypo., gold taking no part in this process. Unfortunately, prints so treated are said to be the least permanent of any; but of that I can bring no actual proof, never having employed the process.

Experiment 2.—Toning by Sulphur.—We have an unwashed silver print here in a twenty per cent. solution of hypo., and to that we now add a few drops of slightly dilute sulphuric acid. It will be seen that a straw-colored substance is immediately liberated, which is sulphur in an exceedingly fine state of division, and this becomes attached to the print. Toning action goes on, through the silver image being tarnished, or, more correctly, converted into sulphide of silver. This liberation of sulphur may be expressed by the following equation:

Hypo.Sulphuric Acid
Na2S2O3 + H2SO4 =
Glauber Salts. Water Sulphur Dioxide Sulphur.
Na2SO4 + H2O + SO2 + S.

With respect to the reaction which takes place when toning a silver image with sulphur, I will quote a few lines from the parent work of reference for nearly all recent writers, namely, Hardwich's Photographic Chemistry, wherein we find the following paragraph:

"It is well known that articles of silver plate become darkened by exposure to the fumes of sulphur, or to those of sulphureted hydrogen, of which minute traces are always present in the atmosphere. If the stopper of a bottle of sulphureted hydrogen water be removed, and a simply-fixed photographic positive suspended over it, the picture will lose its characteristic red tone, and become nearly black. The black color is even more intense than an experienced chemist would have anticipated, because analysis teaches us that the actual quantity of silver present in a photographic picture on paper is infinitesimally small; and it is well known that sulphide of silver, although of a deep brown color, approaching to black when in mass, exhibits a pale yellow tint in thin layers, so that a mere film of silver converted into sulphide possesses very little depth of color. To explain the difficulty it has been suggested that the toning action of sulphur on a red print is probably due to the production of a sub-sulphide possessing an intense colorific power, like the sub-oxide and sub-chloride of silver. When the toned picture is subjected to the further action of sulphur, is converted into the ordinary protosulphide of silver, and becomes yellow and faded."

The toning baths following the sulphur method were principally mixtures of gold terchloride and hypo. This latter substance was found to be a solvent of certain silver compounds by the Rev. J. B. Reade, in 1839, Mr. Talbot having previously fixed his prints with common salt. Prints, too, were fixed first in some cases, and toned afterward, washing away the free silver being more or less practiced in the mixed hypo. and gold and the sulphur toning processes. When fixing was employed before toning, it was usual to soak washed prints in a twenty per cent. solution of hypo. for a period of ten minutes, or until the soluble silver salts were removed, the resulting color being a disagreeable yellowish-brown. To improve the result so obtained the prints were passed into a solution of—

Gold terchloride10grains.
Water20ounces.

When toning action quickly followed, the yellow color giving place to that of a dark sepia tint. From this stage to that of mixing these two substances together was only a natural sequence, and effected a diminution of gold to the extent of one-fourth, as will be seen by the following recognized formula:

Hypo.7ounces.
Water20"

When dissolved, add—

Gold terchloride5grains.
Dissolved in water20ounces.

After mixing, a clear solution should result.

The sel d'or process followed, and was expected to give still better results. It was found, however, that the solutions would not keep; and as a considerable quantity of the gold salt was needed, it caused experimenters to search for a less expensive method. One decided point in its favor was the circumstance that prints suffered no loss of intensity during the operation, as they do in the case of all other toning methods. Briefly: the prints were well washed to extract free silver, and, after soaking five minutes in salt and water, they were passed into an alkaline solution composed of—

Liquid ammonia60minims.
Water20ounces.

Here they became very red. After washing in clean water the surface was flooded with a toning solution composed of

Double hyposulphite of gold and sodium (sel d'or)½grain.
Hypo.1"
Water1ounce.

Upon the print assuming a purple-gray color it was withdrawn and fixed in a sixteen per cent. solution of hypo. to dissolve the unacted upon silver chloride. Gold, when in a fine state of subdivision, is of a rich purple color. The layer obtained by deposition upon a silver image is very finely divided; hence the color. The only object in continuing the toning action beyond the stage at which a good surface color has been reached is to obtain a deposit of sufficient density to completely neutralize the red color of the organic silver image beneath; therefore, it is preferable, in forming a judgment of toning action, to examine proofs by transmitted light rather than by reflected only.

Before dealing with the various formulæ for alkaline toning I should like to step out of the golden track to say a few words on platinum tetracloride, PtCl4.

Experiment 3.—Platinum Toning.—The value of a platinum salt as a toning agent for silver images has been thoroughly demonstrated before you by Mr. Henderson, when he initiated us into the secrets of ceramic photography. My trials with this salt as a toning agent for paper proofs have only been partially successful. By that I mean that toning does take place when a dilute solution is employed, but the action is too tardy for demonstration here to-night, since anything like a black tone could not be obtained under half an hour. You will observe that the surface becomes covered with chloride, showing the necessity for copious washing. Yellow or discolored prints are bleached when toned in this bath, the whites becoming very pure. The formula here given is capable of producing a very good shade of brown in less time, and should be permanent, since platinum is a metal practically unaffected by the atmosphere; and I think there is good reason to suppose that if a thin coating of platinum could be deposited on the silver image, the protection offered would be more economical as well as stable. Something has already been done in this direction, but not in recent years.

The following is the composition we are now using:

Platinum tetrachloride, sirupy solution, color of old East India sherry5minims.
Hydrochloric acid150"
Water20ounces.

Wash away the free silver thoroughly, warm the toning solution to 70° Fahr., and fix in a twenty per cent. hypo. bath.

Mr. A. Watt, in the second volume of the News, gives a formula which runs as follows:

Solution of platinum30minims.
Hypo.3grains.
Hydrochloric acid5minims.
Water5ounces.

This bath is said to act instantly, but I have not had an opportunity to test it. The strength of the platinum solution here given is indefinite, but any of our experimental members can soon ascertain the amount of dilution necessary to obtain the most favorable results.

Alkaline Toning.—Owing to the bleaching action which occurs in toning silver prints with gold, which is slightly acid, certain experiments were made, and it was found that bleaching increased in proportion to the quantity of hydrochloric acid added. Now, in the action of toning chlorine is disengaged, and in order to render this powerful bleaching agent inert it has been proposed to introduce a substance capable of combining with it, and thus, in absorbing it, prevent undue loss of vigor. To obtain this a slightly alkaline toning bath became a necessity, and to Mr. Waterhouse we are indebted for the introduction of the alkaline salts (Hardwich).

Here is an example:

Experiment 4.

Sodium carbonate (Na2HCO3)5grains.
Auric terchloride (AuCl3)1grain.
Water10ounces.

Instead of the dry bicarbonate we will use a saturated solution. In this as well as the following experiments we shall tone three prints of the same subject, viz., ordinary, fumed, and preserved.

Mr. Maxwell Lyte has written on and investigated the properties of toning solutions a great deal more than most men, and we find the following emanating from Mr. Lyte:

Sesquichloride of gold15grains.
Phosphate of soda300"
Distilled water1¾pints.

And in the same communication it is mentioned that 180 grains of borax may be substituted for the phosphate with a like result. Therefore it will be seen that a borax toning bath is not of recent discovery, although it does not appear to have been quoted in many formulæ for at least a dozen years after its publication.

After the publication of Mr. Lyte's formulæ it was found that other salts behaved similarly; and among the first suggested we found sodium acetate, the qualities of which, extolled by the introducer, Mr. Hannaford, have since been verified by the whole photographic world. Here is one of the ordinary formulæ:

Experiment 5.

Gold terchloride1grain.
Sodium acetate10"
"chloride10"
Hot water20ounces.

Mix twenty-four hours before use. Neutralize with chalk or whitening (carbonate of lime).

The name of M. Le Gray must be mentioned as the originator of the lime and gold toning bath; although the original formulæ differ somewhat from the one now used, the results are identical. The original formulæ consisted first in washing away a portion of the free silver by soaking the proofs for a few minutes in two changes of water, then submitting them to the action of an auriferous bath, composed of

Terchloride of gold, 1 per cent. solution1part.
Hyperchloride of lime (white powder)3"
Distilled water1,000"

The action was complete in ten to fifteen minutes, when the prints required washing in two changes of water to free them from the chloride of lime remaining in the fibers previous to fixing in one to six of hypo. If the tone were satisfactory at the expiration of fifteen minutes, the ordinary washing could be proceeded with; if not, the proofs were submitted to a final bath composed of:

Gold terchloride2parts.
Hypo.200"
Distilled water1,200"

M. Le Gray says: "The proof ought not to be left in this bath less than fifteen minutes, as that is the minimum time necessary to insure the permanency of the picture; but it may be allowed to remain in it for as much longer as is requisite for obtaining the desired tone." Efficient washing in warm and cold waters completed the operation. Should any of our provincial members experience a difficulty in obtaining calcium chloride for their experiments, it can be easily made by causing dilute 7 to 3 hydrochloric acid to react on common whitening, and when neutral filter and set aside for the crystals to separate out.

Experiment 6.—The uranium and gold toning bath has many friends. The tones are said to be richer and to economize gold, while it is very easy to work. I am unable to give the author's name, but I can present a formula which has worked well in my hands. After washing away the free silver tone in the following mixture:

No. 1.

One grain acid solution of gold terchloride1ounce.
Water7ounces.

Neutralize with sufficient of a twenty per cent. solution of sodium carb. (Na2HCO3).

No. 2.

Three grain solution of uranium nitrate1ounce.
Water7ounces.

Neutralize as in No. 1. Warm each to 70° Fahr., and mix. The bath is then ready for use. It can be used repeatedly if desired by acidifying with citric acid and neutralizing before use; but nothing is gained by using it a second time.

There are methods of toning which resemble more or less those which have occupied our attention to-night; among them may be mentioned the tungstate bath, likewise citrate of soda. The vermilion bath, too, might afford sufficient matter alone for a lecturette. If some one experienced with it could be induced to bring it before us, I am sure it would prove interesting.