122 DR. P. F. FRANKLAND OR THE QUANTITATIVE ESTIMATION OF 
following day. The results are, therefore, doubtless too low, and only comparable 
inter se. 
V. Laboratory window (same). July 19, 1886. Wind gentle, S. by S.E. Roads and 
pavements quite wet. Raining at time; tube, however, protected by angle of 
building 
No. 1. Morning. Volume of air aspirated = 119 litres. 
Construction of plug. —Glass-wool and glass-powder (yg-" thick). 
Rate .— A.bout 3'6 strokes per minute. 
Plug mixed with 20 c.c. of sterilised water, of which 1 c.c. gave on plate- 
cultivation :— 
Colonies, 36, 48, 45 . . . Average = 43 colonies. 
Two control-plates with same sterilised 
water gave 2, 4 colonies . Average = 3 ,, 
119 litres of air yielded .'. 40 X 20 = 800 ,, 
10 „ „ 67 
No. 2. Afternoon. Volume of air aspirated = 119 litres. 
Construction of plug .—Sugared glass-wool and sugar-powder (yg" thick), but plug 
not otherwise so tight as in No. 1. 
Rate .—About 5'6 strokes per minute. 
Plug mixed with 20 c.c. of sterilised water, 1 c.c. of which gave on plate- 
cultivation :— 
Colonies, 31, 48, 31 . . . Average = 36'7 colonies. 
The above control-plates apply equally 
to this experiment. 
119 litres of air yielded .'. 337 X 20 = 674 ,, 
10 „ „ 57 
N.B.—The plugs in these experiments were not treated until the following day, and 
the results are, therefore, doubtless too low, and only- comparable inter se. 
VI. Laboratory window (same). July 20, 1886. Wind, due S., moderately strong. 
Very heavy rain on previous night. 
Volume of air aspirated = 119 litres. 
Construction of plug .—Sugared glass-wool and sugar-powder. 
Rate. —About 4'9 strokes per minute. 
Plug mixed with 20 c.c. of sterilised water, 1 c.c. of which gave on plate- 
cultivation :— 
Colonies, 26, 25, 35. . . Average = 287 colonies. 
Two control-plates with sterilised water 
gave colonies 4, 2 . . Average =3 ,, 
119 litres of air yielded 257 X 20 = 514 ,, 
10 „ „ 43 
