Medical manual of chemical warfare, 1943 / War Office.

  • Great Britain. War Office.
Date:
1943
Catalogue details

Licence: Public Domain Mark

Credit: Medical manual of chemical warfare, 1943 / War Office. Source: Wellcome Collection.

    5/100 (page 5)
    4. Objects to be achieved by the use of gas. Gas may be used with one or more of the following objects in view :— (a) To produce casualties by using it directly against personnel. . (b) To produce casualties by contaminating stores and niaterial. (c) To harass troops by compelling them to wear respirators for pro- longed periods, and thus to reduce their mobility, efficiency and endurance, and, possibly, lower their morale. (d@) To deny ground by rendering it dangerous to occupy. _(e) To contaminate food and similar stores. (f) To lower the morale of the civil population and induce a will to compromise or surrender. The type of gas used will vary with the object in view. Lethal gases such as phosgene will cause serious casualties among troops, even though they be equipped with efficient respirators, unless their training against gas is of a high | order. Similarly, mustard gas used in shell or from aircraft will cause numerous casualties, in spite of respirators and other protective equipment, if training in their use is defective. Even against troops fully equipped and trained, mustard gas will act as a powerful harassing agent, although casualties in large numbers may be avoided. | The arsenical irritants and lacrimators, when directed against personnel equipped with respirators and trained in their use, should not produce casualties, but they may impair efficiency. 5. Concentration, and period of exposure thereto. It is evident that the higher the concentration of the gas, the shorter will be the period of exposure required to produce casualties among personnel exposed to it ; and the converse holds good. High concentrations can be obtained by liberating the gas in confined or sheltered areas; or, under conditions of open warfare, by the expenditure of an enormous quantity of gas. In the latter case, however, the element of _ surprise is essential if adequate effects are to be obtained on trained personnel, especially when highly irritant gases are used. It should also be borne in mind that, with persistent liquids, a high tem- perature will tend to produce a high concentration of vapour at the cost of persistence, whereas a low temperature will act in the reverse direction. 6. Factors soverning the use of gas. It is obvious that a strong wind will rapidly dilute and disperse all con- centrations of non-persistent gases, while in the case of a persistent gas the rate of evaporation of the liquid will be increased, thus tending to clear the area more rapidly. With a low wind velocity, on the other hand, a high local concentration may be obtained with both types of gases. Temperature plays an important part, both by influencing the diffusion of the gas by convection currents and by affecting the persistence of such liquids as mustard gas; thus warm, sunny weather is inimical to the most effective use of gas. Very cold weather, however, also has its disadvantages, as it reduces very markedly the immediate value of persistent gases: in the case of mustard gas, for example, evaporation will be very greatly reduced as this liquid freezes at comparatively high winter temperatures (about 44° F. for the crude product). On the other hand, mustard gas in the frozen state is not by any means inert, as contact with it will still produce a burn. If the frozen mustard gas is carried (e.g. on boots) to warmer surroundings it will soon liberate effective vapour concentrations.