82 



POPULAR SCIENCE NEWS. 



[June, 1888. 



Tlie beautiful red color is due to traces of 

 cUromium from the bichromate of potash : and, 

 very singularly, when heated they become 

 nearly' black in color, like the natural stones ; 

 regaining their red color in cooling. 



MM. Fremy and Verneuil propose to re- 

 peat their experiments on a larger scale, in 

 the hope of producing much larger gems than 



Fio. 2. 



heretofore. As the sapphire only differs from 

 the ruby in its color, it is probable that, by 

 substituting some salt of cobalt or other blue 

 coloring- matter for the chromium, they could 

 be formed with equal ease. What effect this 

 discovery will have upon the price of these 

 gems remains to be seen ; but if the efforts to 

 produce crystals of considerable size arc suc- 

 cessful, the ruby must necessarily lose its 

 position as the most valuable of all precious 

 stones. ^ 



MATTER MADE INVISIBLE, BUT NOT LOST. 

 In chemical operations, whether natural or 

 artificial, matter is often " lost to sight;" but 

 the veriest tyro has learned, as one of the fun- 

 damental axioms of science, that it can never 

 be actually lost or destroj-ed. In its manifold 

 mutations it often disappears from our vision ; 

 but it reappears, or can be made to reappear, 

 as palpable to our sense as before. If a piece 

 of silver bo put into nitric acid, a clear and 

 colorless liquid, it is rapidly' dissolved, and 

 we " see it no more." The solution may be 

 mixed with water, and apparently no effect is 

 produced. Thus, in a pail of water we may 

 dissolve fifty dollars' worth of silver, not a 

 particle of wliicli can be seen. Not even the 

 chemist, unless he should apply certain tests 

 to detect its presence, would, by merely look- 

 ing at the liquid, guess what hidden wealth it 

 contained. Other metals, as we know, can 

 be treated in similar ways with the same re- 

 sult. When charcoal and many other sub- 

 stances are burned, they disappear as com- 

 pletely, no visible ashes even being left from 

 the combustion. In fact, every material 

 which is visible can, by certain treatment, be 

 rendered invisible. Matter which in one state 



or condition is perfectly opaque, and will not 

 permit a raj' of light to pass through it, will 

 in another form become perfectly transparent. 



The cause of this wonderful change in mat- 

 ter is utterlj- inexplicable. Philosophers may 

 say that it is due to some alteration in the 

 position or arrangement of atoms or mole- 

 cules ; but atoms and molecules, however 

 confident we may be concerning their exist- 

 ence and the laws that govern their mutual 

 attractions and repulsions, are absolutely 

 beyond the reach of our senses. We may see 

 the substances they form, we may guess at 

 changes they undergo ; but we cannot sec 

 them, or do any thing more than guess what 

 they really are. 



We do know, however, that matter is in- 

 destructible — or, at least, that we have nn 

 evidence that it can be destroyed. The sub- 

 stances dissolved in water or burned in the 

 air are not annihilated or lost : by certain 

 well-known means thej- can be recovered and 

 restored to sight ; some in exactly the same 

 state as before their invisibility, others in 

 some other state or condition in which we 

 none the less surely recognize them. If a 

 pailful of the solution of silver be cast into a 

 river, it is apparently lost by its dispersion in 

 the water ; but we are sure that it nevertheless 

 continues to exist. All analogies drawn from 

 experiment show that, however much the solu- 

 tion may be diluted, its component elements 

 are unchanged. So, when a bushel of charcoal 

 is burned in a stove, and the invisible vapor- 

 ous compound produced by the combustion is 

 diffused through the vast atmosphere, we 

 kn6w that the charcoal is still in the air. On 

 the brightest and sunniest day, millions of 

 tons of black charcoal in an invisible condition 

 are floating in the air. Millions of plants are 

 at the same time restoring it to visible form by 

 the chemical processes going on in the tiny 

 laboratory of every leaf that expands in the 

 sunshine. In the course of time the leaf, or 

 the wood it elaborates by its delicate alchemy, 

 may be burned ; and this cycle of change may 

 go on indefinitely, the matter becoming visible 

 and invisible again and again. Tiie poet only 

 expresses a familiar scientific fact when he 

 sings : — 



" Thus the Seer, 

 With vision clear, 

 Sees forms appear and disappear 

 In the perpetual round of strange, 

 Mysterious change 



From birtli to death, from deatli to birtli, 

 From earth to lieavoii, from lieaven to eartli; 

 Till glimpses more sublime 

 Of things, unseen before, 

 Unto liis wondering eyes reveal 

 The Universe as an immeasurable wheel 

 Turning forevermore, 

 In the rapid and rushing river of Time." 



SIMPLE SCIENTIFIC EXPERIMENTS. 

 A PKETTY experiment upon the densitj' of 

 liquids can be performed by taking two glasses 

 of equal size, and filling to the brim, one with 

 wine and tlie other with water (Nos. 1 and 2, 

 Fig. 1). Cover the glass containing water 

 with a piece of writing-paper, and with a' little 



dexterity it may be placed over the glass of 

 wine (No. 3) without spilling a drop. Then 

 draw the paper a little to one side, and the 

 lighter wine will rise, and the heavier water 

 fall, causing two opposite currents between 

 the glasses, until tliey have changed places 

 with each other. The movement will be very 

 evident from the difference in color of the two 



liquids. If wine cannot be obtained, a mixture 

 of one part of alcohol to ten of water, colored 

 with a little ink, may be used instead. 



Into a glass of any effervescing liquid, as 

 champagne or ginger-ale, drop a grape or 

 raisin. It is a scientific law that l)ubhles of 

 gas or vapor when given oflT from a liquid are 

 first developed in contact with the sides of the 

 vessel or some solid l)0(ly in the liquid. In 



Ki(^ 



this case the bubbles will attach themselves to 

 the grape or raisin, and, acting like miniature 

 balloons, will raise it to the top of the liquid, 

 where tliey escape. The fruit will at once sink, 

 onlj- to develoj) more gas-bubbles, and rise 

 again, thus keeping up a sort of dance until 

 the effervescence subsides. 



A MYSTEiuous experiment in " animal mag- 

 netism " maj- be performed bj- taking a piece 

 of paper two or three inches long and half an 

 inch wide, and turning the ojjposite corners up 



