Decontamination of materials / issued by the Ministry of Home Security (Air Raid Precautions Department).

Date:
1936
Catalogue details

Licence: Public Domain Mark

Credit: Decontamination of materials / issued by the Ministry of Home Security (Air Raid Precautions Department). Source: Wellcome Collection.

    11/74 (page 9)
    CHAPTER I. ~ HOW CONTAMINATION ARISES. 1. What Contamination Means. The term contamination is used to signify the pre- sence on the ground, or on any object or person, of a chemical substance, either liquid or vapour, which is capable of giving off what is known as a poison gas. Many war gases are discharged in the form of a liquid, which vaporises on being freed from its con- tainer. Some of these liquids vaporise immediately, and these gases belong to the category known as non- persistent. From other liquids the vapour is given off slowly, sometimes over a period of days and even weeks, and these are known as persistent gases. Contamination arises mainly from the persistent gases, and is caused by splashes of the liquid, or wind- borne spray. Temporary contamination may also be present in the disturbed earth of the crater of a bomb containing a non-persistent gas. The persistent gases with which this book is mainly concerned are:— Tear Gases— Ethyl iodoacetate (K.S.K.). Bromobenzyl cyanide (B.B.C.). Blister Gases— Mustard gas. Lewisite. The blister gases* are by far the most dangerous, and give rise to the major decontamination problem. 2. Types of Contamination. Three sources of contamination may be encountered as a result of air attack:— (1) Fine spray from aircraft. (2) Gross spray from low-flying aircraft. (3) Heavy local contamination from gas bombs. * For their characteristics, effects, and methods of use, see A.R.P. Hand- book No, t.