Page:Popular Science Monthly Volume 2.djvu/135

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tremely common, hundreds of houses in this city being yearly rejuvenated in this way, to the serious injury, no doubt, of their subsequent inmates.


Trees and Rain.—A correspondent writes thus to the Bulletin of the Torrey Botanical Club: "The influence of trees upon rain and the general moisture of the atmosphere, which has been much discussed of late, receives a strong illustration from the island of Santa Cruz, West Indies. A friend who spent the months of February, March, and April last, upon this island, informs me that, when he was there twenty years ago, the island was a garden of freshness, beauty, and fertility. Woods covered the hills, trees were everywhere abundant, and rains were profuse and frequent. The memory of its loveliness called him there at the beginning of the present year, when, to his astonishment, he found about one-third of the island, which is about twenty-five miles long, an utter desert. The forests and trees generally had been cut away, rainfalls had ceased, and a process of desiccation, beginning at one end of the land, had advanced gradually and irresistibly upon the island, until for seven miles it is dried and desolate as the seashore. Houses and beautiful plantations have been abandoned, and the people watch the advance of desolation, unable to arrest it, but knowing almost to a certainty the time when their own habitations, their gardens, and fresh fields, will become a part of the waste. The whole island seems doomed to become a desert. The inhabitants believe, and my friend confirms their opinion, that this sad result is due to the destruction of the trees upon the island some years ago."


Poisonous Paper-Hangings.—In his valuable paper "On the Evil Effects of the Use of Arsenic in Certain Green Colors," published in the third annual report of the Massachusetts State Board of Health, Dr. Frank W. Draper gives the following, among other startling cases of arsenical poisoning from green-colored paper-hangings:

In 1862, a case of fatal poisoning under the conditions in question occurred in the suburbs of London, the victim being a child. The cause of death was made the subject of an investigation before a coroner's jury. In the course of the evidence, it transpired that the deceased was the last of four children who had died within a period of two months, under exposure to the poison contained in the paper-hangings of the room they habitually occupied. They had all been attacked in the same manner, the prominent symptoms being referred to the throat. The color was loosely applied, having no glazing. It was very deliquescent; at 50 it was quite damp, and the stain came off on the hand like paint. Three grains of arsenic were found in a square foot of the paper. The symptoms were attributed by the surgeon in attendance, Mr. Orton, and by Dr. Letheby, who made the post-mortem chemical examination, to arsenical poisoning.

But greens are not the only colors which contain arsenic, nor wall-paper the only fabric colored with arsenical pigments. A correspondent of the Chemical News, who is in a position to know, states that the French use the following-named pigments, containing arsenic, in calico-printing, and that they are equally suitable, and doubtless used, in the color of paper-hangings: Light scarlet pigment contained alumina, arsenious oxide, and aurine; scarlet ponceau contained carbonate of lime in addition to above ingredients; dark green, a preparation of aniline green and arsenious oxide; steam chocolate, and catechu pigment, both contained arsenious oxide. Hallwachs has demonstrated the presence of arsenic in red, as well as in green-colored wall paper.


Volcanic Dust.—The dust discharged at the last eruption of Vesuvius, though very heavy, was carried in one direction to a distance of twenty-five miles, where it fell in quantities sufficient to cause great annoyance to the inhabitants. It consisted of aggregations of crystallized quartz, dotted over with the magnetic oxide of iron. The grains were very uniform in size, and would pass through a wire gauze the apertures of which measured the sixteen thousandth of a square inch. By boiling in hydrochloric acid, the whole of the iron can be removed, and nothing but crystals of fine white quartz remain. Its composition is the same as that of the iron-sand which is found in the soil in some parts of the country round Vesu-