PREPARATION OF LITMUS PAPER.

BY A. VACHER.

I have had much trouble in obtaining a thoroughly satisfactory litmus paper. When used with blotting paper it is not as delicate as could be wished, and on one occasion, when attempting to make it with sized paper, the blue tincture persistently turned red when it touched the paper. The latter reaction seemed to be due to the sizing material, and it occurred to me that if I sized some paper myself with pure gelatin, my object would be obtained.

I can recommend the following receipt:

66

Digest 20 grm. litmus with 100 c. c. water for some time, shaking occasionally; then filter. To the filtrate add a slight excess of nitric acid, and boil; then neutralize exactly with potash. Now make a weak solution of gelatin by boiling 1 part of isinglass with 50 parts of water; draw white blotting paper through this, and hang it up to dry. When dry, paint one side with the above solution of litmus.

20 Great Marlborough Street, May 30.

ODORIFEROUS PRINCIPLE OF FLEUR DE GARANCE AND GARANCINE ALCOHOL.

It is a well known fact that when ground madder root is prepared into garancine, or fleur de garance, a saccharine liquor is obtained which, on fermentation and distillation, yields an alcohol which is contaminated with what, for years past, was considered to be methyl alcohol. More recent researches have brought out the fact that the peculiar odor of the alcohol obtained from the washing liquors of the garancine and fleur de garance works is due to acetic ether, and far more largely to aldehyd. The impure madder spirit, as ordinarily met with in trade, is an excellent source from which to prepare and obtain large quantities of aldehyd ammonia by the following method: From 20 to 30 litres of the impure spirit are placed in a distilling apparatus provided with a long metal (copper) worm, and heated to 60° or 70° C., while at the same time a rapid current

of air, or carbonic acid, is passed over the liquid in the still; the distillation is continued until the distillate ceases to give with solution of caustic potash a darkish coloration. To the distillate twice its bulk of water is added, while in order to decompose the acetic ether, finely powdered hydrate of baryta is added, with continuous agitation of the liquid until a decided alkaline reaction sets in; the excess of baryta is removed by carbonic acid. The aldehyd is afterwards separated from the liquid by careful distillation on a water bath, and purified by combining it with ammonia. If the impure madder spirit is agitated with sodium amalgam, perfectly pure alcohol is obtained; since the aldehyd is by this means hydrogenized to alcohol, and the acetic ether is decomposed into alcohol, while acetate of soda is formed. -Lond. Chem. News, June 26, 1868.

THE CICADA SEPTENDECIM.

During this month, (August,) the Seventeen-year Locust, (Cicada septendecim of Linnæus) has disappeared, and only a few Harvest-flies, as the two other species we have are called, raise their shrill cry during the dog-days. But as this year has been marked by the appearance of vast swarms in the Middle States, we cannot do better than give a brief summary of its history, which we condense from Dr. Harris' work.

The Seventeen-year Locust ranges from South-eastern and Western Massachusetts to Louisiana. Of its distribution west of the Mississippi Valley we have no accurate knowledge. In Southern Massachusetts they appear in oak forests about the middle of June. After pairing, the female, by means of her powerful ovipositor, bores a hole obliquely to the pith, and lays therein from ten to twenty slender white eggs, which are arranged in pairs, somewhat like the grains on an ear of wheat, and implanted in the limb. She thus oviposits several times in a twig, and passes from one to another, until she has laid four or five hundred eggs. After this she soon dies. The eggs hatch in about two weeks, though some observers state that they do not hatch for from forty to over fifty days after being laid. The active grubs are provided with three pairs of legs. After leaving

the egg they fall to the ground, burrow into it, seek the roots of plants whose juices they suck by means of their long beak. They sometimes attack the roots of fruit trees, such as the pear and apple. They live nearly seventeen years in the larva state, and then in the spring change to the pupa, which chiefly differs from the larva by having rudimentary wings. The damage, the larvæ and pupæ do, then, consists in their sucking the sap from the roots of forest and, occasionally, fruit trees.

Regarding its appearance, Mr. L. B. Case writes us (June 15) from Richmond, Indiana: "Just now we are having a tremendous quantity of locusts in our forests and adjoining fields, and people are greatly alarmed by them; some say they are Egyptian locusts, etc. This morning they made a noise, in the woods about half a mile east of us, very much like the continuous. sound of frogs in the early spring, or just before a storm at evening. It lasted from early in the morning until evening.' Mr. V. T. Chambers writes us that it is abounding in the vicinity of Covington, Kentucky, "in common with a large portion of the Western country." He points out some variations in color from those described by Dr. Fitch, from New York, and states. that those occurring in Kentucky are smaller than those of which the measurements are given by Dr. Fitch, and states that "these differences indicate that the groups, appearing in different parts of the country at intervals of seventeen years, are of dif ferent varieties." A careful comparison of large numbers collected from different broods, and different localities, and different years, would alone give the facts to decide this interesting point.

Regarding the question raised by Mr. Chambers, whether the sting of this insect is poisonous, and which he is inclined to believe to be in part true, we might say that naturalists generally believe it to be harmless. No hemiptera are known to be poisonous, that is, have a poison-gland connected with the sting like that of the bee, and careful dissections by the eminent French entomologist, Lacaze-Duthiers, of three European species of Cicada, have not revealed any poison apparatus at the base of the sting. Another proof that it does not pour poison into the wound made by the ovipositor is, that the twig thus pierced and wounded does not swell, as in the case of plants wounded by

Gall-flies, which secrete an irritating poison, giving rise to tumors of various shapes. Many insects sting without poisoning the wound; the bite of the mosquito, black-fly, flea, the bed-bug, and other hemipterous insects, are simply punctured wounds, and to a perfectly healthy constitution they are not poisonous, though they may grievously afflict many persons, causing the adjacent parts to swell, and in some weak constitutions induce severe sickness. Regarding this point, Mr. Chambers writes:

"I have heard-not through the papers-within a few days. past of a child, within some twenty miles of this place, dying from the sting of a Cicada, but have not had an opportunity to inquire into the truth of the story, but the following you may rely on. A negro woman in the employment of A. V. Winston, Esq., at Burlington, Boone County, Ky., fifteen miles distant from here, went barefooted into his garden a few days since, and while there was stung or bitten in the foot by a Cicada. The foot immediately swelled to huge proportions, but by various applications the inflammation was allayed, and the woman recovered. Mr. Winston, who relates this, stands as high for intelligence and veracity as any one in this vicinity. I thought on first hearing the story, that probably the sting was by some. other insect, but Mr. Winston says that he saw the Cicada. But perhaps this proves that the sting is not fatal; that depends on the subject. Some persons suffer terribly from the bite of a mosquito, while others scarcely feel them. The cuticle of a negro's foot is nearly impenetrable, and perhaps the sting would have been more dangerous in a more tender part."-American Naturalist, August, 1868.

ARE LOCUSTS POISONOUS ?

We find a number of items in the newspapers this year claiming that locusts, their bite, sting, or eggs, are poisonous. In Georgia, it is stated that a young lady lost her life by rubbing her teeth with a twig (of cornus Florida, probably, as that is frequently done,) in which a locust had deposited its eggs. And somewhere in the west, fishes are said to have been poisoned by berries in which locusts had deposited their eggs, and which had

fallen into a stream. And the following items we find in the papers:

--

Locust eggs appear to be very deadly in their poisonous effects. A party of little boys were recently killed by eating mulberries in which they had been deposited, and so rapid was the work of the poison, that they died under the trees from which they took the berries.

The death of a little girl at Kimmswick, Mo., resulting from the sting of a locust, is noted by the local papers.

Now, "e'en from our boyish days," in the south and southwest, we were familiar with all kinds of locusts, handled and played with them constantly, and knew other children to do the same, and the worst thing we ever knew or heard about them was their intolerable music. This idea of their being poisonous, is a new one to us-but, then, this is Presidential year, and it may be that the locusts have become innoculated with the "poison of politics," hence the trouble!

If, however, the locust is really poisonous, it should be known, and our readers will confer a favor by reporting their observations on the subject.-Editor Med. Surg. Rep., Aug., 1868.

OBSERVATIONS ON FERRIC HYDRATE.

BY PROFESSOR ATTFIELD, Ph.D.

In a memoir, noticed in the Chemical News of June 12th as having been recently presented to the Academy of Sciences, M. Jeannel, in allusion to the fact that ferric hydrate is not always soluble in acids, states that the incomplete solubility is, in his opinion, generally due to the influence of traces of sulphates. He says, according to the Paris correspondent of the Chemical News, "sesquioxide, precipitated from the persulphate, is always to a certain extent insoluble, or yields unstable salts; the same is the case with the sesquioxide precipitated from the perchloride, when this has been contaminated by sulphuric acid, or equally when the alkalies employed as precipitants have been so contaminated, or, finally, when the ferric hydrate, precipitated from pure solutions by pure alkalies, has been washed with common water.” This explanation does not accord with my experience of the properties of ferric hydrate and oxyhydrates. Firstly, in Eng