Substances which seem useful for producing skin burns are studied both on animals and on man. Dichloroethyl sulfide (mustard gas) is used as a basis of comparison. Several methods are available.
Direct Application. This method consists of the direct application of the compound itself to the skin, using a definite quantity (0.005 cc. or 0.005 mg.) over a definite area (5 square centimeters) of the skin. With such a quantity of mustard gas a rather severe burn on animals is produced. No precautions are taken to prevent evaporation from the skin since it is believed that in this way the test will approximate fairly closely the field conditions.
Vapor Tests. Preliminary tests with vapors of volatile compounds are best made by placing a small amount of the material on a plug of cotton in the bottom of a test tube enclosed in a larger test tube which acts as an air jacket. After about an hour at room temperature the mouth of the test tube is applied to the skin. The concentration is not known, but one is dealing practically with saturated vapor. If an exposure of from 30 to 60 minutes produces no effect, one is safe to assume that the compound is not sufficiently active to be of value as a skin irritant.
If quantitative results are desired, the apparatus shown in [Fig. 119] is used. Dry air is blown through the bubbler, which is connected with a series of glass skin applicators. The concentration is determined in the usual way. The skin applicator consists of a small cylinder about 1.5 to 2 cm. in diameter and about 4 cm. long with a small glass handle attached on top. The opening is 1 cm. in diameter. When the concentration of the gas is constant, the exposure to the skin is made directly for any desired length of time. The skin irritant efficiency is judged by comparing the per cent of positive responses to approximately equal concentrations of the vapors, using mustard gas as a standard.
TABLE I—Physical and Physiological Properties
of Chemicals Used as Stenches
| Chemical | Boiling Point, °C. | Freezing Point, °C. | Character of Odor | Physiological Properties of Vapor | Remarks |
|---|---|---|---|---|---|
| Amyl acetate | 148 | -75 (thick) | Banana oil | Harmless | Pleasant to most people; disagreeable to some |
| Ethyl acetate | 77.4 | -83.8 | Fruity, pleasant | Harmless | |
| Amyl alcohol | 137.8 | Alcoholic | Harmless | ||
| Butyric acid | 162.3 | -7.9 | Very disagreeable | Harmless | |
| Valeric acid | 186.4 | -58.5 | Very disagreeable | Harmless | |
| Ethyl ether | 35 | -112.6 | Pungent | Soporific | |
| Phenyl isocyanide | 165 | Very disagreeable | Unknown | ||
| Allyl isothiocyanate | 151 | Mustard oil, disagreeable | Lachrymatory and toxic | ||
| Methyl isothiocyanate | 119 | 34 | Mustard oil, disagreeable | Lachrymatory and toxic | |
| Amyl isovalerate | 190 | Very disagreeable | Harmless | ||
| Butyl mercaptan | 97 | Very disagreeable | Harmless | ||
| Isobutyl mercaptan | 88 | Very disagreeable | Unknown | Probably harmless | |
| Ethyl mercaptan | 37 | -144.4 | Very disagreeable | Harmless | |
| Propyl mercaptan | 67 | Very disagreeable | Unknown | Probably harmless | |
| Methyl salicylate | 222.2 | -8.3 | Oil of wintergreen, pleasant | Harmless | |
| Amyl thioether | 95-98 | Very disagreeable | Unknown | Probably harmless | |
| Ethyl thioether | 92 | -99.5 | Very disagreeable | Unknown | Probably harmless |
| Carbon tetrachloride | 76.74 | -19.5 | Sweet, unpleasant | Harmless | |
| Chloroform | 62 | -63.2 | Sweet, agreeable | Soporific | |
| Iodoform | Decomposes | 119 | Unpleasant | Harmless | |
| Artificial musk | Pleasant | Harmless | Unpleasant in higher concentration | ||
| Nitrobenzene | 209.4 | 5.71 | Almonds, pleasant | Toxic | |
| Oil of peppermint | Pleasant | Harmless | |||
| Pyridine | 115.2 | -42 | Very disagreeable | Toxic |
TABLE II—Results of Measurement of the Intensity
of Various Stenches
| Chemical | Volumes of the Chemical, as a Perfect Gas, per Million Volumes of Air, Intensity of Odor | ||||
|---|---|---|---|---|---|
| Detectable | Faint | Quite Noticeable | Strong | Very Strong | |
| Amyl acetate | 7 | 10 | 13 | 90 | 246 |
| Ethyl acetate | 190 | 339 | 615 | 1236 | 1753 |
| Amyl alcohol | 63 | 83 | 123 | 439 | 601 |
| Butyric acid | 2.4 | 6 | 18 | 91 | 161 |
| Valeric acid | 7 | 29 | 125 | 332 | 962 |
| Ethyl ether | 1923 | 3352 | 4927 | 5825 | 19982 |
| Butyl mercaptan | 6 | 12 | 18 | 38 | 56 |
| Isobutyl mercaptan | 3.5 | 5 | 7 | 11 | 16 |
| Ethyl mercaptan | 18 | 35 | 73 | 141 | 198 |
| Propyl mercaptan | 2 | 7 | 9 | 14 | 17 |
| Amyl thioether | 0.2 | 1 | 1.6 | 1.7 | 2.2 |
| Ethyl thioether | 3 | 12 | 29 | 61 | 74 |
| Allyl isothiocyanate | ?2 | 3 | 6 | 8 | 50 |
| Methyl isothiocyanate | 5 | 13 | 23 | 36 | 48 |
| Amyl isovalerate | 1.7 | 3 | 6 | 10 | 12 |
| Carbon tetrachloride | 718 | 1461 | 1588 | 4964 | 6091 |
| Chloroform | 674 | 1389 | 2600 | 5887 | 19528 |
| Iodoform | 1.1[35] | ||||
| Artificial musk | |||||
| Nitrobenzene | 29 | 36 | 44 | 114 | 296 |
| Phenyl isocyanide | 0.5 | 1 | 3 | 10 | 25 |
| Pyridine | 10 | 45 | 93 | 700 | 1764 |
| Methyl salicylate | 16.1 | 23 | 29 | 244[36] | |
| Oil of peppermint | |||||
| Chemical | Milligrams of Chemical per Cu. Ft. of Air, Intensity of Odor | ||||
|---|---|---|---|---|---|
| Detectable | Faint | Quite Noticeable | Strong | Very Strong | |
| Amyl acetate | 1.1 | 1.5 | 2 | 14 | 38 |
| Ethyl acetate | 19.4 | 34.6 | 63 | 126 | 191 |
| Amyl alcohol | 6.4 | 8.5 | 13 | 45 | 61 |
| Butyric acid | 0.3 | 0.6 | 2 | 9 | 16 |
| Valeric acid | 0.8 | 3.4 | 15 | 39 | 114 |
| Ethyl ether | 165.1 | 287.7 | 423 | 500 | 1715 |
| Butyl mercaptan | 0.5 | 1.0 | 2 | 3 | 5 |
| Isobutyl mercaptan | 0.2 | 0.5 | 0.7 | 1 | 2 |
| Ethyl mercaptan | 1.3 | 2.5 | 5 | 10 | 14 |
| Propyl mercaptan | 0.2 | 0.6 | 0.8 | 1.2 | 1.6 |
| Amyl thioether | 0.04 | 0.2 | 0.3 | 0.4 | 0.5 |
| Ethyl thioether | 0.3 | 1.2 | 3 | 6 | 8 |
| Allyl isothiocyanate | 0.2 | 0.3 | 0.7 | 0.9 | 6 |
| Methyl isothiocyanate | 0.4 | 1.1 | 2 | 3 | 4 |
| Amyl isovalerate | 0.4 | 0.5 | 1 | 2 | 2.3 |
| Carbon tetrachloride | 128 | 260 | 283 | 886 | 1087 |
| Chloroform | 93 | 192 | 360 | 816 | 1321 |
| Iodoform | 0.5[37] | ||||
| Artificial musk | 0.001[38] | ||||
| Nitrobenzene | 4 | 5 | 6 | 16 | 42 |
| Phenyl isocyanide | 0.06 | 0.1 | 0.4 | 1 | 3 |
| Pyridine | 0.9 | 4 | 9 | 64 | 162 |
| Methyl salicylate | 2.8 | 4 | 5 | 43[39] | |
| Oil of peppermint | 0.68 | 0.9 | 3 | 9.5 | 9.9 |
| Chemical | Milligrams of Chemical per Liter of Air, Intensity of Odor | ||||
|---|---|---|---|---|---|
| Detectable | Faint | Quite Noticeable | Strong | Very Strong | |
| Amyl acetate | 0.039 | 0.053 | 0.067 | 0.478 | 1.326 |
| Ethyl acetate | 0.686 | 1.224 | 2.219 | 4.457 | 6.733 |
| Amyl alcohol | 0.225 | 0.300 | 0.442 | 1.581 | 2.167 |
| Butyric acid | 0.009 | 0.021 | 0.066 | 0.329 | 0.580 |
| Valeric acid | 0.029 | 0.119 | 0.523 | 1.394 | 4.036 |
| Ethyl ether | 5.833 | 10.167 | 14.944 | 17.6667 | 60.600 |
| Butyl mercaptan | 0.018 | 0.037 | 0.055 | 0.120 | 0.177 |
| Isobutyl mercaptan | 0.008 | 0.018 | 0.025 | 0.041 | 0.060 |
| Ethyl mercaptan | 0.046 | 0.088 | 0.186 | 0.357 | 0.501 |
| Propyl mercaptan | 0.006 | 0.020 | 0.028 | 0.043 | 0.054 |
| Amyl thioether | 0.001 | 0.007 | 0.0115 | 0.012 | 0.015 |
| Ethyl thioether | 0.012 | 0.042 | 0.107 | 0.223 | 0.271 |
| Allyl isothiocyanate | 0.008 | 0.012 | 0.024 | 0.030 | 0.201 |
| Methyl isothiocyanate | 0.015 | 0.039 | 0.067 | 0.108 | 0.144 |
| Amyl isovalerate | 0.012 | 0.018 | 0.039 | 0.072 | 0.082 |
| Carbon tetrachloride | 4.533 | 9.222 | 10.024 | 31.333 | 38.444 |
| Chloroform | 3.300 | 6.800 | 12.733 | 28.833 | 46.666 |
| Iodoform | 0.018[40] | ||||
| Artificial musk | 0.00004[41] | ||||
| Nitrobenzene | 0.146 | 0.178 | 0.222 | 0.563 | 1.493 |
| Phenyl isocyanide | 0.002 | 0.005 | 0.013 | 0.042 | 0.105 |
| Pyridine | 0.032 | 0.146 | 0.301 | 2.265 | 5.710 |
| Methyl salicylate | 0.100 | 0.145 | 0.179 | 1.526[42] | |
| Oil of peppermint | 0.024 | 0.032 | 0.109 | 0.332 | 0.348 |