BACTERIOLOGICAL AND LABORATORY TECHNIQUE.
Section IV.
Lieut.-Col. W. F. HARVEY, m.a., m.b., d.p.h., c.i.e., i.m.s., Director, Central Research Institute, Kasauli. [Received for publication, May 9, 19 U.]
S 7 STANDARDIZATION.' Notes. — '.A term used here to indicate conceptions such as potency, measurement, titration, standard character, etc. S 7.1 TURBIDITY. S 7.11. — (1) Set up a series of picked T.T. all of the same calibre. (2) Prepare the following solutions : — No. 1, 1 per cent chemically pure sulphuric acid and No. 2, 1 per cent pure barium chloride. (3) .A.dd definite proportions of No. 1 aol. to No. 2 sol. to give standard turbidity suspensions as follows : — 99 c.c. No. 1 sol. tc 1 c.c. No. 2 sol.. 98 c.c. No. 1 sol. to 2 c.c. No. 2 sol., 97 c.c. No. 1 sol. to 3 c.c. No. 2 sol, and so on down to 90 c.c. No. 1 sol. to 10 c.c. No. 2 sol. (4) Place convenient quantities of the resulting suspensions in the picked T.T. and seal ofi these T.T. in the blow pipe flame. (5) Compare' the turbidity of the test suspension placed in a T.T. of the same calibre as those containing the standard suspensions with these suspensions. (6) Find- with which suspension in the standard series the test sihspcn-sion corresponds. Nttel. — 'This is best done by placing each of the standard Kunpeunicm T. T. in succession alongside the test suspension in a good light over clearly printed matter. •The t< »t KUitpension may require dilution to bring it within the range of the standard series. In that case the degree of dilution must be taken into account in calculating the strength of the test suspension. J, MR ( 405 ) 1
