DISINFECTION AND DISINFECTANTS. 55 



of connecting the standard types of mixed nations with the races com- 

 posing them. The stature-curve of England differs visibly in propor- 

 tions from that of Italy, the measurements of Scotch and American 

 soldiers show very different mean and extreme terms, and the problems 

 of race underlying these differences are of a most complex character, 

 the more so when the consideration is introduced of the race-type 

 varying within itself from century to century. M. Quetelet is natural- 

 ly apt, when expressing his views in an exordium or a peroration, to 

 draw a good deal on the anticipated future results of his admirable 

 method; but in judging of the value of his doctrine of central types, 

 the best criterion is his actual success in reducing the observed facts 

 of Nature to numerical calculation. The future must show how far it 

 will be possible to apply to the theory of species the definition of cen- 

 tral specific forms, from which varieties calculably diminish in numbers 

 as they depart in type. Nature. 



-++*- 



DISINFECTION AND DISINFECTANTS. 



By WILLIAM EASSIE, C. E. 



THERE are certain rules to be promulgated respecting the protec- 

 tion of human life from contagion, or from the injurious effects 

 of decomposing organic matters, which may be gleaned from the ex- 

 perience of ages, and which as yet have never been laid down with 

 sufficient clearness. 



A writer in a medical journal, the other day, pointed out, from the 

 " Odyssey " of Homer, the great solicitude of Ulysses for the purification 

 of his house with sulphur, and the history of purgation could go still 

 farther back, and bring to light many other interesting memorabilia. 

 This, however, hardly comes within the scope of these short papers ; 

 neither, as I said before, would any attempt to explain the cause of 

 disease, for it would only be a repetition of wise things said before. 

 Happily, too, the grim dwellers of the threshold are now watched with 

 eye of lynx and nerve of steel, and their newer thrusts at poor mankind 

 met or parried. Names like those of Drs. Parkes and Sanderson, in 

 this respect, are fast becoming household words. For the purposes of 

 this chapter, however, I cannot forbear from condensing the remarks 

 of Dr. Angus Smith, with respect to disease generally. According to 

 this authority, the classes of disease may be caused firstly, by gases 

 easily diffused in air, such as carbonic acid, nitrogen, marsh-gas, and 

 others ; secondly, by vapors falling in cold air and. taken up in fogs, 

 volatile bodies in fact, that concentrate in cool temperatures, and not 

 to be classed with gases ; thirdly, by putrid or decomposing substances, 



