ia> Till-; AMKiiK AN MONTHLY |Mav. 



tains vast munbcis of more or loss pertcctlv recotjni7.al>lc tVaji^- 

 incnts of imisclc (lorivcti tVoni tlic meat oaten as tood. Tlic iVafj- 

 incnts arc not in the conilition of cooked meat, l>ntare so modified 

 bv tlu" dij^estive process as to l>e no loiiijer solnlile in a warm 

 acid solnti<»n of" pepsin. They are also insoluble in a dilute warm 

 sohition of" caustic potash, .\j4ain, thev resist decomposition t"or 

 a far lon«;er time than cooked meat, when kept in water: at tiie 

 same time showiii}; the microscopical structme of" muscle witii 

 such marvellous perf"ection that the\ cannot la- contoiuided witli 

 any other object. 



{T,) Human f'a-ces vary in composition accordinj^; to the f"ood 

 eaten. Cireen ve<;etables t"urnisii many spiral vessels, while f";eces 

 from oatmeal abound in the hairs of oats. 



(4) Morse excrements play the most important part in street 

 washing^s. Their most ciiaracteristic objects are hairs of oats and 

 spiral vessels derived from straw or <^reen fodder. 



(5) It is quite within the possibilities of our present know 1- 

 edgc to i)repare a microscopical scale of comparison bv the use 

 of whicii to estimate the amount of scwaj^e contamination in any 

 p^iven sample of water. 



The f"orej2;oin<^ discussion presents a few of the points to be 

 taken into account in determining the various circumstances aflbct- 

 innj the (juality of a public water supply. Without pretending; to 

 legitimately make all the deductions from this inadccpiate pres- 

 entation of some of the elements of the subject, we may still lay 

 the following down as practical points to be borne in mind when 

 studying questions of sanitation in relation to public water sup- 

 plies, namely : 



(i) The circumstances affecting the quality of a public water 

 supply are of an exccedinglv complex nature. So true is tiiis 

 that what appears to be a cause of disease at one time mav pos- 

 sibly become under difVerent conditions the source of immimity 

 from danger. Hence a knowledge of the detail is indispensable 

 for a really rational decision in nearly everv case. 



(2) The most complete system of chemical study thus far de- 

 vised is the combustion method of Dr. Frankland. but the diffi- 

 culty of working it has prevented its general adoption in actual 

 work. At the present time, by reason of the perfection of the 

 systems of biological examination, the simpler albuminoid am- 

 monia process of Wanklyn answers all the re(]uirements of the 

 purelv chemical stutiv. 



(3) Dr. Frankland's method of estimating the previous sew- 

 age or animal contamination is interesting as showing how com- 

 pletely he realized, twenty years ago, the value of more definite 

 inffjrmation about the natural history of water. 



(4) The working out of exact methods of studying the bac- 

 teria about ten vears ago was a great step in advance in determin- 

 ing the sanitary relations of potable water. 



(5) The working out in the last three years of exact methods 



