422 



SCIENCE. 



is to say, if one impregnates with it fresh bonillo7i, the 

 latter is completely sterile. Up to that time life exists 

 in the vase exposed to air and heat. If we examine the 

 virulence of the culture at the end of two days, four 

 days, six days, eight days, etc., it will be found that long 

 before the death of the culture the microbe has lost all 

 virulence, although still cultivable. Before this period it 

 is found that the culture presents a series of attenuated 

 virulences. Everything is similar to what happens in 

 respect to the microbe in chicken cholera. Besides, each 

 of these conditions of attenuated virulence may be re- 

 produced by culture ; in fact, since the charbon does not 

 operate a second time {ne recidive pas), each of our 

 attenuated anthracoid microbes constitutes for the 

 superior microbe a vaccine — that is to say, a virus capa- 

 ble of producing a milder disease. Here, then, we have 

 a method of preparing the vaccine of splenic fever. You 

 will see presently the practical importance of this result, 

 but what interests us more particularly is to observe that 

 we have here a proof that we are in possession of a gene- 

 ral method of preparing virus vaccine based upon the 

 action of the oxygen and the air — that is to say, of a 

 cosmic force existing everywhere on the surface of the 

 globe. 



" I regret to be unabie, from want of time, to show 

 you that all these attenuated forms of virus may very 

 easily, by a physiological artifice, be made to recover 

 their original maximum virulence. The method I have 

 just explained of obtaining the vaccine of splenic fever 

 was no sooner made known than it was very extensively 

 employed to prevent the splenic affection. In France 

 we lose every year, by splenic fever, animals of the 

 value of twenty million francs. I was asked to give a 

 public demonstration of the results already mentioned. 

 This experiment I may relate in a few words. Fifty 

 sheep were placed at my disposition, of which twenty- 

 five were vaccinated. A fortnight afterward the fifty 

 sheep were inoculated with the most virulent anthracoid 

 microbe. The twenty-five vaccinated sheep resisted the 

 infection ; the twenty-five unvaccinated died of splenic 

 fever within fifty hours. Since that time my energies 

 have been taxed to meet the demands of farmers for 

 supplies of this vaccine. In the space of fifteen days we 

 have vaccinated in the departments surrounding Paris 

 more than twenty thousand sheep, and a large number 

 of cattle and horses. If I were not pressed for time I 

 would bring to your notice two other kinds of virus 

 attenuated by similar means. These experiments will 

 be communicated by-and-by to the public. I cannot 

 conclude, gentlemen, Without expressing the great pleas- 

 ure I feel at the thought that it is as a member of an 

 international medical congress assembled in England 

 that I make known the most recent results of vaccina- 

 tion upon a disease more terrible, perhaps, for domestic 

 animals than small-pox is for man. I have given to 

 vaccination an extension which science, I hope, will 

 accept as a homage paid to the merit and to the immense 

 services rendered by one of the greatest men of England, 

 Jenner. What a pleasure for me to do honor to this 

 immortal name in this noble and hospitable city of 

 London ! " 



FROM a privately issued report on silk cultivation in 

 the Chinese province of Kwangtung, we learn that in the 

 I'akhoi district, on the southern seaboard, wild silkworms 

 are found which feed on the camphor tree, and their 

 silk is utilized in a singular manner. When the cater- 

 pillar has attained its full size, and is about to enter the 

 pupa state, it is cut open and the silk extracted in a form 

 much resembling catgut. This substance, having under- 

 gone a process of hardening, makes excellent fish line, 

 and is generally used for that purpose in the Pakhoi dis- 

 trict. 



CORRESPONDENCE. 



[The Editor does not hold himself responsible for opinions expressed 

 by his correspondents. No notice is taken of anonymous communis 

 cations.} 



To the Editor of " Science." 



Mr. Samuel J. Wallace, commenting on my paper on 

 " The Use of Water as a Fuel " ("Science," Vol. II., p. 

 321), in an interesting communication to you ("SCIENCE," 

 Vol. II., p. 373), suggests an inadvertancy on my part in 

 " not more clearly distinguishing between the degrees of 

 temperature at which the transfer of oxygen takes place 

 from the hydrogen of the water to the carbon set free by 

 the dissociation of the naphtha and the number of heat 

 units set free or absorbed by such transfer, which is a 

 very different thing." 



To this I would state in reply that I have purposely re- 

 frained from an elaborate calculation of the thermal ef- 

 fects in heat units for several reasons. Of these I shall 

 detail but a few of the more important at present. 



In the first place, my intention was to give the scien- 

 tific rationale of the chemical processes involved in the 

 generation of the tremendous heat produced by the Hol- 

 land retort with so insignificant an amount of naphtha ; 

 and, furthermore, I wanted to show that the application 

 of the principle of the correlation of forces and conserva- 

 tion of energy to this new and original process of combus- 

 tion has been undertaken heretofore on an erroneous as- 

 sumption ; lastly, I intended to prove, in the shortest and 

 clearest possible manner, what a proportion of heat was 

 gained, and in what manner — viz., by the dissociation of 

 steam in the presence and by the agency of the carbon 

 contained in the naphtha. 



For these and other reasons, I avoided long explana- 

 tions and calculations of other points, such as, for instance, 

 the "dissociation of the naphtha," as Mr. Wallace puts it, 

 and the figuring up of the heat units generated by the 

 several elements on combustion. In order to re-affirm my 

 position, which is, on most points, not that assumed by 

 Mr. Wallace, I may be allowed to offer the following re- 

 marks : 



It is self-evident that the carbon of the naphtha, in 

 order to act independently, must first -be set free ; this is 

 accomplished by the heating of the naphtha, in its cham- 

 ber of the retort, up to the point of gasification. On meet- 

 ing the steam in the manifold, the carbon of the naphtha 

 leaves its hydrogen and forthwith unites with the oxygen 

 of the watery vapor, forming either carbonic oxide or 

 carbonic acid, according to the amount of steam intro- 

 duced. 



Thus there is certainly a decomposition of the naphtha 

 into its elements, as Mr. Wallace intimates ; but by far 

 the most important process is the dissociation of the 

 watery vapor which Mr. Wallace refuses to recognize, 

 insisting, as he does, that there is only a transfer of the 

 oxygen from the hydrogen of the steam to the carbon of 

 the naphtha. How this is possible, without the previous 

 dissociation of the steam, I am unable to understand. 

 Mr. Wallace furnishes, indeed, the best argument against 

 his own statement, by mentioning the well-known fact 

 that the carbon in the naphtha is very loosely held by 

 its hydrogen. But it is also a well-known fact that the 

 oxygen of the steam is very tenaciously held by its hydro- 

 gen, so much so that it was considered impossible to 

 separate, to dissociate, them by heat for a long time. Not 

 until the late Henri St. Clair Deville * devised an appa- 



* It is with profound grief that the announcement of the great chemist's 

 death has been received everywhere. At his funeral (July 5th) M. Pas- 

 teur made an eloquent speech. The London Chrwicat News has an obitu- 

 ary in which occurs the following passage: "His highest achievement, from 

 a strictly scientific point of view, was the establishment of the laws of dis- 

 sociation. Previously, decomposition was regarded as a simple phenom- 

 enon, effected and completed, in the case of every substance, at a fixed 



I temperature. Deville showed that in some cases it is effected within cer- 

 tain limits of temperature, being arrested at a given heat by the equi- 

 librium established between the decomposing body and the product of de- 



I comp;sition." 



