464 



APPENDIX 



the same principle applies to a well not in regular use. Such a well 

 should be pumped for some time before taking the sample. For obtain- 

 ing samples from a considerable depth Miquel's apparatus may be used, 

 or, if that is not available, a weighted bottle. 



After collection, the bottle should be at once stoppered, labelled, and 

 packed in ice and sawdust for transport to the laboratory, or placed in 

 one of the various ice cases now in use (Delepine's or Pakes'). Below 

 5 C., organisms do not multiply in water, and therefore it is important 

 to keep samples previous to examination at a low temperature. In all 

 cases where it is possible, the water should be examined at once after 

 collection. 



Physical Examination. The temperature and reaction of the water 

 should first be tested, and an examination made of any deposit or 

 suspended matter. Bubbles of gas, if present, should be noted. The 

 colour, character, and amount of particulate matter in suspension or 

 sediment should be observed and noted ; turbidity, odour, flavour and 

 taste, peatiness, etc., should all be noted. A record of the quantity of 

 the sample, its source, and the date and time of its collection is also 

 important. A microscopical examination of the matter obtained by 

 filtration followed by centrifugalisation may also yield important facts. 



Bacteriological Examination. This divides itself naturally into two 

 divisions (a) a quantitative examination, and (V) a qualitative examina- 

 tion.* 



0) Quantitative Examination 



The sample should be gently mixed, and plate cultivations made. 

 Take five tubes of 10-15 c.c. of gelatine and five Petri dishes, and melt 

 the medium of the former in a water bath. The gelatine should be well 

 liquefied, but not overheated. The Petri dishes should be of even 

 surface, equal size, and properly sterilised. Take a 1 c.c. sterilised 



r%. ^^n 



FIG. 43. Levelling Apparatus for Koch's Plate. 



FIG. 44. Moist Chamber for Koch's 

 Plate. 



pipette accurately calibrated, and pass it into the bottle, removing the 

 necessary quantities of water. As a rule, 0*5 c.c., 0*2 c.c., O2 c.c., 

 O'l c.c., and 0*1 c.c. are suitable quantities for each of the five plates. 

 Add these quantities to the five tubes of liquefied gelatine, and gently 



* An admirable illustration of how to examine a water is furnished in the Report 

 of Medical Officer to Local Government Board, 1901-2, pp. 494-547 (Houston). 



