RECORD: Darwin, C. R. 1871.08.05. Using common pin. CUL-DAR54.71. Edited by John van Wyhe (Darwin Online, http://darwin-online.org.uk/)
REVISION HISTORY: Transcribed by Christine Chua and edited by John van Wyhe 5.2022. RN1
NOTE: See record in the Darwin Online manuscript catalogue, enter its Identifier here. Reproduced with permission of the Syndics of Cambridge University Library and William Huxley Darwin. The volumes CUL-DAR 54-61 contain material for Darwin's book Insectivorous plants (1875).
[71]
Albury Aug. 5 – 1871
Using common pin I removed from two different minim glasses 5
(These are Pins used)
minims by taking drops on head of pin, & drying it by touching blotting–paper & then removing whole drop. – No doubt the glands of Drosera wd not remove so completely - I thus found that 300 of my drops = 5 minims. ∴ 1 minim = 60 drops. Of course this not absolutely accurate, but very near. I find by mark on blotting paper, pin being immersed vertically, that drops very equal – an average result from 5 or 6 wd be almost exactly equal.
See over for Table,—
[71v]
60 Pin Head drop = 1 minim
Pin-Head drops Minims
300 = 5.
12/3600 = 12/60 = 1 drachm
8/28,800 = 8/480 = 1 oz
Hence in solution of 1 gr to 1 oz one of my drops would contain 1/28,800 of substance.
If 1 drop acted on 3 Heads
28,800 [x] 3 [=] 86,400
what proportion by weight on nitrogen in 100 part of dry carbon of ammon
carbon of ammon
Citation: John van Wyhe, ed. 2002-. The Complete Work of Charles Darwin Online. (http://darwin-online.org.uk/)
File last updated 25 September, 2022