Connecticut western news., 1877-05-11
SCIENTIFIC.

the market any kind of invisible ink for postal cards. Although we do not believe that such ink would prove very
 useful, it would probably meet with considerable sale, partially from the novelty of the thing. Many kinds of magic ink have been known for years, but most of them possess some disad- vantage. A writer in the Deutsche In. dustrie Zeitung, in discussing the subject, claims that postal card ink should possess the following properties: l.. The writing must, of course be invisi-
 ble at first. 3. It must be of such a nature as to be rendered visible quickly and easily by means in the possession of every one at all times. 3. There should not be several kinds of this ink in market, one of which is developed | by light, another by heat, a third by common salt solution, etc., so that, on receiving a blank card, the receiver would be at loss to know how to de- | velop it. This writer then goes on to recommend the use of a solution of nitrate or chloride of cobalt, mixed with a little sugar or gum to make it flow easily from the pen. Such writing is
 made visible by moderate heat, even a burning match being sufficient. Dr. Bottger, in note to this article, recom
 mends the use of ferrocyamde of potas- ! sium, or yellow prussiate of potash, which is readily developed by the sul- phates of copper and iron '(blue O1 green vitriol), the former yielding brown. the latter blue, letters. Dr. Bottger is an exceedingly fngen- ious chemist, and most Of his sugges- tions are very practical, but we beg to differ with him this time. Very few aI, I posed to have solutions of either blue or green vitriol always at hand; and even a chemist, unless notified to this effect beforehand, would not think to try the effect of these solutions until he had tried several other reagents. This could be remedied by writing on the back of the card with common black ink an ambiguous or nonsensical sen- tence containing the name of the de- veloper to be employed. For chemists, a convenient ink would be solution of some lead salt, which is developed by sulphuretted hydrogen.
 | For ordinary use the most convenient ink is an iron salt; the common tinc- ture of iron of the drug store will answer, if diluted. This writing is scarcely perceptible when dry, but comes out a beautiful black on pouring over it some ordinary green or black tea. The tannin in the tea unites with the iron to form black ink precisely like that used for ordinary correspon- dence.
 l Another ink, less convenient for the writer, but more convenient for the re- ceiver, is to write on the card with thin starch paste. When perfectly dry, the card is flowed with a solution of iodine in very strong alcohol. This imparts a reddish color to the card, but does not develop the writing, owing to the absence of water. The receiver has the writing will appear in blue charac- ters. We offer this as suggestion to manufacturers of magic inks. Of course, the operation of flowing with tincture of iodine might be left for the person who receives it, provided he
 were furnished with a key to the de- veloper required. In this case dilute alcohol, or solution of iodide of potas- sium, could be employed as solvent for the iodine.
 | Another method, more curious than useful, consists In writing on the card with solution of paraffiin in benZol. When the solvent has evaporated the paraffiin is invisible, but becomes visible on being dnsted with lampblack or powdered graphite, or smoking over a candle flame.
 Bedvers in CdlitorniG.-The Stockton
 (Cal.) Independent publishes the follow
 ing: ''As the jules of this vicinity
 abound in beavers, numbers of hunters
 and trappers have made an excellent
 living in capturing them for their pelts
 The latter are worth $2.50 each, and an
 industrious trapper can catch from 3C
 to 50 month. In the equable climate
 of California the time of year seems tc
 have no especial effect on the excellence
 of the beaver fur, it being equally good
 in summer and winter. The trappeI
 can, therefore, pursue his avocation
 uninterruptedly the year through
 With the beaver he can catch and the
 other game he can send to market, ar
 industrious man can make $10O month
 and live as his own master. The trap
 per's outfit for the San Joaquin jules is
 a peculiar one. Two hunters usually
 join together in the outfit of an ark, ol floating house, with which they paddle
 out through the innumerable sloughs that intersect the painless jungle o1 jules. The ark affords one small room or cabin, provided with sleeping hunks i, nuu AuII W1Iu 6GOtC dIlN COIulOI U
 always having a shelter, while it's com pact shape and size allows it to float 1T
 the smallest stream, thus bringing tht hunter and his home in the very mids of his game"
 MOrti fcdtion and Wdter.-Professor J , M. Merrick, writing to the AnsericG' Chemist, says: ''In Hofman's Manual l and doubtless in many other chemis ? tries, directions are given for exhibiting the decomposition of water by sodium the hydrogen gas being collected in , l tall, narrow jar by pushing pellets O } sodium under its mouth with wir' } gauge spoon, etc. In both cases I uset F very small bits of sodium. Having 7 blown an expensive glass tube to frag ments in my own laboratory by thi 5 process, and having, in the presence O 5 large class, blown into minute atoms with noise like thunder, large tub ) and porcelain cistern, covering mysel 5 with modification and water, and. cut t ting gashes in my hand, venture t. 7 suggest that possibly there is risk il 8 this experiment, as laid down in tn S books.''
 t You are right Professor. There i
 certainly 8 possibility of risk; ;
 indeed, we are willing to go further and say that there are absolute dangers Lucky that your eyes escaped injury 3 Such experiments should be banishe' l from the lecture room.
 = Hydrioddte of Morphine.-This nev :, compound, which permits of being use, s in medicine, has been prepared b. r Earnst Schmidt both by dissolving nor n phine in hydriodic acid and by the ac 0 tion of acetate of morphine on iodide 0 - potassium. The product in both case was identical. Both crystalline in lon e needles, with silky luster and groupe a in rosettes. The composition is repre- s sented by the formula c H NO H I, an n 2H O. When heated to the temperatur