Scientific American.

[NOVEMBER 17, 1894.]

The Disappearing Photograph.

A sheet of ordinary white, unsized printing paper, or blotting paper, is to be immersed in a liquid made by dissolving twenty grains of gelatine in an ounce of water. When the paper is thoroughly saturated, it is to be hung up to dry. After thorough drying, it is to be floated for three or four minutes on a mixture of one part saturated solution of bichromate of potassium to two parts water, and again dried. The paper is now

There are 24,000,000 of them, and the Dutch government has never had the slightest trouble with any of them."

THE NEW CURE FOR DIPHTHERIA, GROUP, ETC.

If the facts placed before the Hygienic Congress held at Budapest last month be not overstated, then the whole world owes a deep debt of gratitude to the young French savant, Dr. Roux, for the patient and

not only impervious to the toxin, but destroys it, and from this singular result is due the origin of the new substance with which Dr. Roux wages war against diphtheria. In a word, it is the basis of a great revolution in the medical world, which henceforth will recognize in "Serum therapy" a heaven-sent system to roovent most of the diseases meted out with childhood. As Dr. Marsan well says, there are toxins and anti-toxins for all microbe affections. Serum therapy will eventually discover a remedy for all infectious diseases. Yesterday it was tetanus in animals that it cured, to-day it is diphtheria, to-morrow it will be tuberculous.

If you go to the Institut Pasteur, you will find comfortably stalled in the garden some ten or a dozen cab horses, in prime condition, aged from six to nine years, whose mission in life it is to furnish the precious fluid which every day snatches many a young life from an untimely grave. They are in their measure unconsciously solving the problem of how to stop the depopulation of France. They are well cared for, there is no cruelty in the process, no suffering entailed. The first process is to inject the deadly virus—the toxin—into the shoulder of the horse. This, of course, at first causes a slight indisposition, but after a while no ill effect is felt. The second step, as shown in one of the views, is to draw from the neck of the "prepared" animal a judicious quantity of blood. If the blood be allowed to stand for a while, the red corpuscles settle to the bottom, and the operator can then draw off the fluid, of a yellowish hue, resting above and containing the serum, or antitoxin. This, in its turn, is injected under the skin of the patient by means of a syringe analogous to that used for injecting morphine.

On February 1 of this year Dr. Roux began operations at the Hospital for Sick Children, Paris. He had a good supply of serum, and each day on making his visit to the hospital, he treated all the children he found there, in whatever state or condition of croup or diphtheria. There was no selection of subjects, a point to be borne in mind. nor was the ordinary treatment in any way modified or set aside. Things went on exactly as they had before, except that a new element had been introduced—namely the serum. During 1890, 1891, 1892, 1893, before Dr. Roux began his system, 3,971 children suffering from croup and diphtheria were admitted into the Hospital for Sick Children. Of these 2,029 died of the disease, the mortality thus being 52 per cent. On the other hand, from February 1 of this year up to July 24, the date up to which Dr. Roux furnished statistics to the Congress, the serum was applied to all without exception, and, out of 448 children, there were but 109 deaths—that is, the mortality had decreased to 24 per cent. As the conditions during these periods were the same, the difference between 52 per cent and 24 per cent indicates the indisputable benefit derived from Dr. Roux's treatment. If we take the same period at the Trousseau Hospital, Paris, where the old methods prevail, we

THE NEW CURE FOR DIPHTHERIA, GROUP ETC.—INJECTING THE SERUM.

sensitive to light, and must be kept in a dark place. By exposure to the sun under a negative, for a sufficient time, a brownish print is produced, which is first to be soaked in cold water, until the unaltered bichromate of potash is dissolved out, and then in warm water, which removes all the gelatine that has not been rendered insoluble by the combined action of bichromate of potash and light. On the completion of this operation, the picture is still visible, in a faint brown color, but, by immersion in a solution of sulphurous acid, this color is bleached out, and, on drying, the paper appears perfectly white all over, without the faintest trace of an image. In order, however, to bring out the image, all that is necessary is to immerse the paper in what the British Journal calls "hydroxyl monohydride," in other words, clean water, whereupon the picture plainly appears, in white on a dark ground. On drying, it disappears again, and the process may be repeated as often as desired.

heroic researches which have led to the discovery of an effectual cure for croup and diphtheria, and opened the way for further results not less startling. Such is the introductory announcement in the London Daily Graphic, which also gives the following:

The distinguished Dr. Marsan points out how the new method was established. Diphtheria is produced by microbes which plant themselves in the membrane of the throat, and multiply; but unlike the bacilli of other infectious diseases, they remain obstinately in the same position, neither penetrating the system nor the blood. But if the deadly animacules remain at the door, they are still able to secrete a poison of extreme violence, called "toxin," which quickly pene-

Java Tea and Coffee.

W. C. Knoofe, a rich coffee and sugar grower of Java, is among the recent arrivals at the California, says the San Francisco Examiner. He has lived in Java ten years and has large and flourishing plantations.

He told an interesting story recently about this queer country, for so many years under the control of the Dutch, and said that few persons understand the strange conditions of life there.

"You never saw such happy people anywhere as these little Javanese. They are always talking, laughing and dancing, and seem never to have any sort of care. They work in the tea, coffee and sugar plantations for 8 or 9 cents a day, and the best of them never get over 10 or 12 cents. Yet they are entirely contented. The women, who are the best for tea pickling, do not get more than 4 or 5 cents a day. The tea is cut every forty days, so that there is always work to do. There is a big yield this year, and it is good tea, but it isn't worth much. We got word from Amsterdam, where much of our tea goes, that it was worth only from 9 to 10 cents a pound.

"With coffee and sugar the price is different. There never was as much money in sugar as at the present time. It is worth from $3.20 to $3.60 for each pioul, or 134 pounds. The growers are getting rich. Both the coffee and sugar crops are very large, and like the tea, they are very fine. Coffee has veered around so much that there is no longer much money in it. All that is grown must be sold to the government. That is a requirement. It is cheap. In Holland it is worth but $6 for each 134 pounds.

"All the labor used is Javanese. It would not pay us to employ any other, and, though the wages are small, the people are probably the happiest on the globe. Their wants are few, the climate is so mild that little is worn, and they are as jolly as the day,

THE NEW CURE FOR DIPHTHERIA—PREPARING THE TOXIN.

trates the circulation and infects the whole body. This toxin, thanks to the achievements of science, can now be isolated, and in the form of a fine powder will cause almost immediate death when injected into animals. However, it has been found that if a very small dose be introduced into certain animals, especially the horse, only a feeble reaction is produced. By repeating the operation, with gradually increasing doses, the organism of the animal finally revolts, and becomes

find that out of 520 children admitted there, 316 died, thus giving a mortality during the months in question of 60 per cent.

But this is not all. The serum, if applied, say, to a child suffering from quinsy, not only puts that ailment to flight, but renders the subject impervious to croup and diphtheria; and even measles and scarlatina are found to be of very rare occurrence, and then only of slight character, when the system has been fortified by