HA RD WICKE'S SCIENCE- G OSSIP. 



227 



affinity of the sodium of the salt for the oxygen of the 

 water, and of the chlorine of the salt for the hydrogen 

 of the water. These affinities not being strong 

 enough to cause double decomposition, an indefinite 

 compound is formed, having the properties of what 

 we call a solution. He illustrates this theory by 

 many examples, which decidedly support it, but there 

 are some serious exceptions, especially among or- 

 ganic substances, such as the solid and liquid hydro- 

 carbons, where the solvent and the dissolved solid 

 are nearly identical in composition. I have only read 

 an abstract of Mr. Durham's papers, and therefore 

 am uncertain whether he has fully considered these. 



Another Use of Bee-Stings. — At a recent 

 meeting of the Physiological Society of Berlin in 

 February last, Dr. Mullenhoff referred to a treatise 

 by Kepler, that appears to have been forgotten, on 

 the structure of the cells of bees. He treats the 

 subject mathematically, as might be expected of the 

 great astronomer. A fact was communicated to this 

 meeting which is very interesting, and new to me, 

 though possibly already known to some of my readers. 

 It is that when the bee has filled the cell either with 

 pure honey, or a mixture of pollen-dough and honey, 

 and has completed the lid, a drop of formic acid 

 obtained from the poison bag connected with the 

 sting is added to the honey by perforating the lid 

 with the sting. Numerous experiments show that 

 this formic acid preserves honey and every other 

 sugar solution from fermentation. If this be well 

 established, it will show that the sting and the poison 

 apparatus of the bee has a further purpose than that 

 ■of a defensive or offensive weapon. Another interest- 

 ing fact suggests itself in connection with this. So 

 far as I know, most of the insects that have stinging 

 .apparatus similar to that of the bee are collectors and 

 storers of honey. 



Inoculation for Yellow Fever. — While the 

 anti-vaccination people are denouncing the principle 

 of inoculation, Pasteur is extending its application to 

 the prevention of cattle disease, chicken cholera, and 

 hydrophobia ; and in the other hemisphere Dr. 

 Domingos Freire, of Rio de Janeiro, is applying it to 

 the prevention of the local scourge of yellow fever. 

 M. Rebourgeon, in a paper communicated to the 

 Biological Society of Paris, described the results 

 obtained by himself and Dr. Freire in December, 

 January, and February last, when the weather of 

 Brazil was intensely hot, and the fever raging accord- 

 ingly ; 3051 subjects were inoculated at Rio, and not 

 .one died, while in the same districts and houses 278 

 of the non-inoculated were killed by the disease. 

 The number of inoculated has since reached 6000, 

 and not one of them has been attacked with fever; 

 and what is still more remarkable, inoculation in the 

 . second stage of severe attacks of the fever was followed 

 .by recovery in every case. 



I am told by those who have lived in yellow fever 

 districts that when a man or woman has a mild 

 attack and recovers, the illness is regarded as a 

 subject for congratulation ; only those who have thus 

 been naturally inoculated can regard their lives as of 

 much prospective value. A second and milder 

 attack is still more fortunate, as nearly perfect immu- 

 nity is then secured. This being the case, the 

 practical conclusion is obvious. If it is possible so 

 to attenuate the virus as to ensure a mild and con- 

 trollable attack, every sane human being who is 

 compelled to live in the midst of this terrible danger 

 would avail himself of such protection with the same 

 readiness and resignation as he would submit to a 

 necessary surgical operation. 



Pile Driving by Dynamite. — The " Society of 

 Arts Journal " tells us that this has been lately carried 

 out by a Hungarian engineer, who fixes horizontally 

 on the top of the pile to be driven a circular cast iron 

 plate, r5 inches in diameter, and 3J inches thick. A 

 dynamite cartridge in the form of a disc 6 inches in 

 diameter, and 5 of an inch thick, containing 17! 

 ounces of dynamite, is placed on the cast iron plate, 

 and exploded by electricity. It is stated that the 

 depth to which the pile is driven by each explosion 

 " is equal to five blows of an ordinary pile-engine 

 weighing 14J Vienna hundredweights, falling 9 feet 

 10 inches," and that a cast iron plate resists on an 

 average 25 explosions. This is interesting as a scien- 

 tific experiment, but in practical working on a large 

 scale, I suspect that five lifts of the pile-engine monkey 

 will cost less than the dynamite, and the wear and 

 tear of the engine less than the breakage of the cast 

 iron plates, to say nothing of the risk that always 

 accompanies the handling of large quantities of 

 dynamite ; and such quantities must be very large 

 where 17J ounces are exploded at every blow on each 

 of a large number of piles. 



How to Keep Cool in Hot Weather.— In 

 " Iron : ' of August 12th, some good practical advice 

 is given concerning the cooling of cellars, or rather 

 the keeping them cool. Many people ventilate their 

 cellars in summer-time in order to keep them cool 

 and dry. Such ventilation has exactly the opposite 

 effect ; it just makes them damp and warm. The 

 temperature of a closed cellar or other underground 

 cavity of moderate depth corresponds nearly to the 

 annual mean temperature of the air above ; therefore 

 in summer it is cooler than the air, in winter it is 

 warmer. It is evident enough that such being the 

 case, the ventilation by means of air at summer tem- 

 perature must warm the cellar. But this is not all. 

 The quantity of water which a given quantity of air 

 is capable of holding in solution varies with the 

 temperature, and this variation is veiy great, a differ- 

 ence of twenty degrees Fahrenheit about doubles the 

 capacity of air for water. Therefore if warm saturated 



