Maech 7, 1902.] 



SCIENCE. 



379 



toxicity. (5) Boiling with a .2 per cent, 

 aqueous solution of hydrochloric acid has 

 but little, if any, effect upon the germ cell 

 or its contained toxin. (6) Heating the 

 germ substance for an hour at the tempera- 

 ture of the water-bath with water contain- 

 ing from one to five per cent, of hydro- 

 chloric acid lessens but does not destroy 

 the toxicity of the cell. (7) The toxin may 

 be partially separated from the cell wall 

 by digestion of the whole with hydrochloric 

 acid and pepsin. (8) With the dried bac- 

 terial cells rabbits may be immiinized to 

 the colon bacillus. (9) Rabbits thus im- 

 munized furnish an antitoxic serum. This 

 antitoxic serum agglutinates the colon ba- 

 cillus and precipitates the toxin from sus- 

 pensions in water. 



H. W. Conn. 



WeSLEYAN UNn'EESITY. 



TBE NEW VAPOR-ENGINES. 



The recent announcement from Berlin 

 of the successful construction of a new 

 'binary- vapor,' or, as the writer has been 

 accustomed to designate it, ' series- vapor 

 engine,' and the almost simultaneous ac- 

 count in the Paris technical and scientific 

 journals of a ' newly invented ' ether-vapor 

 engine, are reviving an old-time error. The 

 distinction between the latter of the two 

 systems and the former, between a fallacy 

 and known truth, as fundamental ele- 

 ments of the revival of these classes of 

 heat-engine, is once more a subject of mis- 

 conception with the technical and even, 

 often, with the scientific writers describing 

 them. 



Professor Josse, at the great Charlotten- 

 burg technical school, and his co-workers 

 among the steam-engine builders of Berlin, 

 have been for some time at work determin- 

 ing the practicability of utilizing the 

 binary-vapor system of heat-engine, sup- 

 plementing the steam-engine by a 'waste- 

 heat engine ' in which a more volatile vapor 



is employed to transform into useful me- 

 chanical energy the large fraction of heat 

 rejected from the former.* The system is 

 old, well-known and entirely correct, ther- 

 modynamically. 



The real qiiestion of the moment which 

 is sought to be solved is the practical one: 

 With our refined systems of design, con- 

 struction and manipulation, to-day, is it 

 possible to practically, safely and con- 

 veniently and, above all, economically em- 

 ploy this system, often previously tried 

 and found wanting, and to thus secure, for 

 the user, a larger return of power for the 

 unit of expenditure and for the life of the 

 ' plant ' than by use of the steam-engine 

 alone ? Can dividends be increased through 

 an unquestionably greatly improved ther- 

 modynamic transformation of energy? 



There is here no question of thermody- 

 namics or of a possibility of dynamic gain ; 

 the experiment has often been tried and 

 this possibility exhibited beyond question. 

 It is noAv a matter of choice of secondary 

 fluid, of safety, permanence of construc- 

 tion, convenience, reliability, ultimate 

 gain in returns on the investment and 

 operative costs. It is now thought, by 

 those most familiar with the facts of this 

 new case, that this problem has at last been 

 solved and that the ' series- vapor engine ' 

 will find a permanent place in the arts. 

 Time and experience will confirm or refute 

 their conclusions. 



Susini, in Paris, on the other hand, has 

 introduced a ' new ' vapor-engine in which 

 he substitutes ether for steam, maintaining 

 that the machine is advantageous as a pri- 

 mary rather than as a secondary or waste- 

 heat engine, and, if his reporters are cor- 

 rect, basing his claim to this superiority 

 upon the assertion that ether, with its 

 volatility and low latent heat of vaporiza- " 



* Mittheilungen aus dem Maschinen-Laborato- 

 rium der Kgl. Techn. Hochschule zu Berlin, 

 1901. 



