“It should furthermore be pointed out that the increase in the chloropicrin service time of charcoal from 18 to 50 min. does not represent anything like a proportionate increase in its value under field service conditions. This is partly due to the fact that the increased absorption on the high concentration tests is in reality due to condensation in the capillaries, which, as has been pointed out, is not of much real value. More important than this, however, is the fact that most of the important gases used in warfare are not held by adsorption only, but by combined adsorption and chemical reaction, for which purpose an 18-min. charcoal is, in general, almost as good as a 50-min. charcoal.” TYPICAL ABSORPTIVE VALUES OF DIFFERENT CHARCOALS AGAINST VARIOUS GASES LEGEND: (A) = H₂O Content, (%) (B) = Accel. Chloropicrin Service Time, (Min.) (C) = Chloropicrin (D) = Phosgene (E) = Hydrocyanic Acid (F) = Arsine (G) = Cyanogen Chloride (H) = Trichloromethylchloroformate (I) = Chlorine ---+-----------------+--------+---+-----+--------------------------- | | | | | Service Time, Minutes | | | | | Standard Conditions No.| Charcoal | Nation | | +---+---+---+---+---+---+--- | | |(A)| (B) |(C)|(D)|(E)|(F)|(G)|(H)|(I) ---+-----------------+--------+---+-----+---+---+---+---+---+---+--- 1 |Poor cocoanut |U. S. A.| 0 | 10 |120|175| 20| 18| 55| 50|270 2 |Medium cocoanut |U. S. A.| 0 | 30 |350|260| 25| 25| 65| 65|370 3 |Good cocoanut |U. S. A.| 0 | 60 |620|310| 27| 30| 75| 70|420 4 |Same as No. 2 | | | | | | | | | | | but wet |U. S. A.|12 | 18 |320|330| 35| 16| 35| 95| 5 |No. 2 impregnated|U. S. A.| 0 | 35 |400|700| 70|400| 70|190|510 6 |Wood |French | 0 | 2.5| 25| 75| 9| 0| 1| 20| 7 |Wood |British | 0 | 6 | 70| 90| 18| 4| 5| 30| 8 |Peach stone |British | 0 | 16 |190|135| 30| 25| 65| 60| 9 |Treated wood |German | 0 | 42 |230|105| 20| 20| 22| 25| 10 |No. 9 impregnated|German |30 | 9 | 90|320| 16| 1|110|120| ---+-----------------+--------+---+-----+---+---+---+---+---+---+--- STANDARD CONDITIONS OF TESTS Mesh of absorbent 8-14 Depth of absorbent layer 10 cm. Rate of flow per sq. cm. per min. 500 cc. Concentration of toxic gas 0.1 per cent Relative humidity 50 per cent Temperature 20° Results expressed in minutes to the 99 per cent efficiency points. Results corrected to uniform concentrations and size of particles. SODA-LIME