HARDWICKE'S SCIENCE-GOSSIP. 



cockroach which was liquoring up on the threshold 

 of a fresh cup that had caught but little or no prey. 

 " After feeding a short time the insect went down 

 the tube so tight (the expression is Mrs. Treat's, the 

 italics are mine) that I could not dislodge it, even 

 when turning the leaf upside down and knocking it 

 quite hard. It was late in the evening when I ob- 

 served it enter. The next morning I cut the tube open, 

 the cockroach was still alive, but it was covered with 

 a secretion produced from the inner surface of the 

 tube, and its legs fell off as I extracted it. From all 

 appearance the terrible Sarracenia was eating its 

 victim alive. And yet perhaps I should not say 

 terrible, for the plant seems to supply its victims with 

 a Lethe-like draught before devouring them." When 

 a large number of insects have been thus enticed and 

 devoured a most offensive odour is perceptible, but 

 the putrid matter does not appear to injure the plant, 

 it absorbs it all and is nourished thereby. Pieces of 

 fresh raw beef and mutton are similarly covered with 

 the digestive secretion and the blood extracted from 

 them, but they must be fresh, and are not so com- 

 pletely absorbed as the live game. At the end of 

 three or four days all the remains of flies, beetles, 

 cockroaches, &c, are absorbed, excepting their wings 

 and other hard parts. 



Triumphant Simplicity. — That most powerful 

 engine of modern research, the spectroscope, depends 

 upon dispersion, i.e. the varying refrangibility of the 

 different rays of light and their consequent outspread 

 when passed through a prism of refracting material. 

 Glass is generally used, but the dispersive power of 

 glass is far exceeded by that dense, though volatile 

 liquid, bisulphide of carbon. One prism-shaped glass 

 trough filled with this liquid, will do the dispersion 

 work of a train of five solid glass prisms, and allows 

 much more light to pass through. Then why make 

 any more spectroscopes of solid glass? is a natural 

 question. The reason is that inequality of temperature 

 produces convection currents in the liquid, and these 

 currents produce strise that spoil the delicate defini- 

 tion of the spectral lines. 



The "American Journal of Science," vol. 29, 

 p. 269, tells us that the defect has been overcome 

 by H. Draper, by two of the simplest devices con- 

 ceivable. As the convection currents are caused by 

 inequality of temperature, he regulates the tempera- 

 ture, and further prevents inequalities of density of 

 the liquid by keeping it stirred by means of a small 

 propellor wheel, driven by a nominal amount of 

 power obtainable by watchwork or a small electro- 

 motor. 



Impermeability of Glass to Gases.— Many of 

 my readers will remember the celebrated Florentine 

 experiment, which was formerly supposed to demon- 

 strate the general porosity of matter. A hollow 

 sphere of gold was filled with water and then squeezed 



in a screw press, so as to diminish its internal 

 capacity. As the experiment proceeded, the water 

 was seen to ooze through the solid metal, and bedew 

 the outer surface of the flattened ball. Gases pass 

 through metals upon much smaller provocation, as 

 may be very unpleasantly proved by using a small 

 unlined iron stove for heating a room, and allowing 

 the sides of the stove to become red-hot. Carbonic 

 oxide passes through the iron of its own accord, and 

 makes its presence known by poisoning the atmo- 

 sphere. This carbonic oxide, resulting from the 

 semi-combustion of the coal, is an active acrid poison. 

 It must not be confounded with carbonic acid, 

 which results from complete combustion, and is only 

 unbreatheable, but not actively poisonous. 



A. Bartoli has made a number of experiments of 

 excessive severity for testing the possibility of forcing 

 mechanically, or coaxing chemically, various gases 

 through glass, and finds it absolutely impermeable. At 

 a pressure of 126 atmospheres (1890 lbs. on the 

 square inch) not even infinitesimal quantities passed 

 through. Electrical devices were equally ineffectual. 



Blind Fishes in Artesian Wells. — In last 

 year's "Journal of Science," page 567, I find it 

 stated on the authority of" The American Naturalist," 

 that J. D. Caton has discovered a species of blind 

 fishes in an Artesian well in California, the depth of 

 which is 170 feet, and that Artesian wells in the 

 Eastern States have already yielded eighteen species 

 of sightless fishes. 



Can this be true ? If so, it is very wonderful 

 indeed. How did the fishes get there ? How long 

 have the wells existed ? The United States are not 

 palaeozoic, nor does the date of the invention of 

 Artesian wells carry us far back in geological time. 

 If so great an organic change can be so extensively 

 evolved during the short life of these artificial 

 sinkings, Darwin and his disciples must be wrong in 

 demanding such long periods of time for other 

 evolutions, and we may hope to demonstrate the 

 origin of species in zoological stations and physio- 

 logical laboratories sufficiently endowed to be in- 

 herited by our grandchildren. That is " if." 



Charring Timber. — It appears that the practice 

 of chairing the lower part of posts that are to be 

 driven into the ground has not the preservative 

 effect generally attributed to it. "Iron" tells us 

 that, "numerous trials have shown that charring 

 leads to premature decay ; " that if two posts are splic 

 from the same log, and one be charred and the other 

 not, the charred post will perish before the other. It 

 is quite true that the charring does protect the surface 

 so far as it goes, and if the post could be charred 

 throughout, without weakening it, the protection 

 would be perfect ; but the superficial charring only 

 weakens the material in proportion to the depth to 

 which it extends — the charcoal, being porous, admits 



