— 302 — 



supersaturation with ammonia was changed to a hright 

 brown-yellow ; but the quantity was so small that the 

 animal matter could not be isolated. 



It is evident from these experiments that the bad 

 odour of night soil is produced almost entirely by ema- 

 nations of a volatile product of putrefaction, soluble in 

 water which is carried up and intensified by admixture 

 with ammoniacal gas, ai<olher product of putrefaction ; 

 and that to this volatile organic matter, the malificent 

 eff-^cts of the emanations from night soil must in chief 

 part be referred. Mackbride has shewn that the addi- 

 tion of a" extremely minute, an almost inappreciable 

 quantity of liquid that exudes from putrefying flesh, is 

 capable of inducing the most rapid putrefaction of fresh 

 meat placed in water ; and it can be easily ur^derstood, 

 how the entrance of minute quantities of the volatile 

 animal matter from putrefying substances into the blood 

 of healthy persons, especially when long continued, 

 should induce disease, or at least render persons so ex- 

 posed more liable to succumb to the action of the poi- 

 sons that produce epidemic diseases. 



We have here an experimental investigation of the 

 chief cause of the bad odour of night-soil, which must 

 not be attributed, as has been done, to sulphuretted hy- 

 drogen or other inorganic compounds resulting from 

 putrefaction. We have collateral proofs that the pre- 

 sence of a far larger proportion of sulphurretted hydro- 

 gen, than could possibly arise from putrefaction of night 

 soil and similar animal or vegetable matters, in the sur- 

 rounding atmosphere does not give rise to fever, or act 

 in the same manner on human health as the emana- 

 tions from putrescent matters. The attendants at the 

 baths of Harrowgate and other sulphureous mineral 

 Avaters, who are constantly inhaling, throughout the 

 day, an atmosphere strongly impregnated with siilphe- 

 retted hydrogen, do not suffer from fever or other dis- 

 ease to a greater extent than persons under ordinary 

 circumstances ; although when mixed in btrger propor- 

 tion with atmospheric air, sulphurrettpd hydrogen is a 

 powerful poison. Berzelius, the celebrated Swedish che- 

 mist, who must, in his numerous analytical processes 

 Jilnftost daily have inspired an ulmosphere containing 



