34 ' EEPORT — 1864. 



gallon of the waterf? of the Water of Leith before reaching Edinburgh, of the spring 

 water supplied to Edinburgh and Leith. of the liquids conveyed by the sewers, 

 and of the Water of Leith after receiving sewage, and including the Lades and 

 harbour of Leith. It may be stated that the analyses marked * were made on a 

 day in spiing, and the remainder were made on a day in summer. 



From the above Table it will be observed that the spring water supplied to 

 Edinburgh, as also the waters which form the sources of the Water of Leith, 

 contain about 29 per cent, of oxvgen iu the gases dissolved therein ; and as the 

 Water of Leith passes several paper-mills and arrives at Coltbridge, where it meets 

 the sewage of Edinburgh, the amount of oxygen is fully 22 per cent, of the gases. 

 The gases dissolved in the liquids conveyed by the sewers contain only from 2-10 

 to 3-3.3 per cent, of oxygen ; and when the sewage has mingled with the Water of 

 Leith, the percentage of oxygen in the main stream falls to 10-20 and even to 4-10, 

 and in the Lade to 5-40 and even 4-76. 



These experimental facts demonstrate that the amount of oxygen dissolved m 

 the water of^the Water of Leith, after receiving the sewage of Edinburgh, is reduced 

 to a minimum, and is practically of little use in consuming the large amoimt of 

 organic matter in solution and suspension iu the water; and moreover shows that, 

 even were the more foul impurities to be separated from sewage and streams 

 conveying sewage, the liquid, though it might be clear, would not contain that 

 amount of oxygen gas dissolved therein which would admit of fishes living in it, 

 and finding tlie air required for their respiration. Trials have been made by the 

 author with water obtained ft'om irrigatiug meadows, and -ndth the water of the 

 Water of Leith, after separation of the gross impurities by mechanical filtering-beds 

 of sand and clay, and the water in either case did not possess the power of supporting 

 the life of fish ; and, indeed, when the fish were introduced therein, they quickly 

 died. 



A Suggestion on the Detection of Poisons by Dialysis. 

 By Dr. A. T. Machattie, F.C.S., Lecturer on Chemistry, Glasgow. 

 The author suggested that in some cases it might be of advantage to employ 

 the coats of the stomach or intestines of an animal as the membrane or septum of 

 the dialyzer, and in this way avoid interference with the organs themselves. This 

 can the more readily be done, since the exterior of the stomach of animals is 

 seldom coated with any appreciable amount of fatty matter, and therefore the 

 whole preparation necessary seems to consist in thoroughly washing the exterior 

 of the stomach or intestines to be examined ; for thereafter the organ may be at 

 once exposed to the external action of pure water, as in the commonly pursued 

 methods of dialysis. This manner of detecting poison need not entirely prevent 

 the previous examination of the interior lining of the stomach, provided that the 

 opening be made so as to enable the stomach to be afterwards suspended in water 

 without mechanical leakage. The intestines of an animal supposed to be poisoned 

 scarcely require to be opened throughout their entire length, and accordingly a 

 portion of them left imtouched maybe tied firmly at each end, washed carefully, and 

 exposed to the external action of water for twenty-four hom-s, or longer if necessary, 

 in the usual way. Into a portion of the duodenimi of a sheep, one-half of a grain 

 of arsenious aci"d was placed, dissolved and suspended in water. This part of the 

 duodenum, after being washed, was tied at each end and suspended in eight 

 oimces of water, in such a manner as to keep tlie tied ends entirely out of the 

 water, and so prevent the contents from escaping by any opening that might stiU 

 exist. The liquid, after twenty-four hom-s, yielded arsenic by Eeinsch's process ; but 

 no appreciable precipitate was obtained by treating the liquids with hydrochloric and 

 hydrosulphuric acids. The author described a similar experiment which he had 

 • made with strychnine. 



On the Presence of NicJcel in Metallic Lead. 

 By Dr. A. T. Machattie, F.C.S., Lecturer on Chemistry, Glasgow. 

 ! Ilavino- had occasion recently to examine several specimens of lead for commercial 

 purposes^I was surprised to find that one of them contained a considerable quantity 



