138 
DR. P. F. FRANKLAND ON THE QUANTITATIVE ESTIMATION OF 
Rate. —5 7 strokes per minute. (Tube exposed 12 minutes.) 
7 . . n 7 , . ^ r 59 moulds. 
Colonies m flasks. — (a) 69 j ^ ^ 
(h) o. iq ' 
Control-tube, containing plug of sugared glass-wool only, exposed 44 minutes; 
flask contained 0 colonies. 
10 litres of air yielded, therefore, in 
No. 1 (glass-wool), 31 colonies. 
No. 2 (sugar-wool), 38 ,, 
VI. Roof of Science Schools. October 11, 1886. Wind S.W., very gentle. Roads 
wet, pavement dry. 13 0, 3 C. Comparison between two sugar plugs, one of 
which had become partially converted into caramel in sterilisation; the two 
tubes were alternated in aspiration. 4.34 p.m. to 5.21 p.m. 
No. 1. Volume of air = 21 litres. 
Construction of plugs. — (a) Sugared glass-wool (not charred). 
( b ) Sugared glass-wool and sugar-powder. 
Rate. — 6‘6 strokes per minute. (Tube exposed 13 minutes.) 
. . n 7 , . 25 moulds. 
Colonies m flasks. — (a) 321 
J ' ' l 0 licp 
f 2 moulds. 
< 6 > 3 l0 liq. 
No. 2. Volume of air =21 litres. 
Construction of plugs. — (a) Sugared glass-wool (partly charred). 
(b) Sugared glass-wool and sugar-powder. 
Rate. —4 strokes per minute. (Tube exposed 19 minutes.) 
_ 7 . . _ 7 . . r 24 moulds. 
Colonies m flasks. — (a) 39 j ^ ^ 
(b) o. iq '' 
Control-tube, containing plug of sugared glass-wool only, exposed 51 
minutes :— 
. . a , r 16 moulds. 
Colonies m flask, 171 
l 0 liq. 
This corresponds to 1 organism in 3 minutes gaining access to the 
plugs; 4 colonies must, therefore, be subtracted from No. 1, and 
6 colonies from No. 2. Thus 
t r • - 7 7 7 7 /. • [No. 1, 15 colonies. 
10 litres of air yielded, therefore, in V T 
J J ’ 1 No. 2, 16 
