Inflation and deflation are effected by an injector driven by compressed oxygen; this alternately drives fresh air enriched with oxygen into the lungs and then by suction empties them again. While with the mechanical appliances of resuscitation belonging to older systems the hand of the helper regulated the rate of breathing, in the case of the Pulmotor the lungs, according to their size, automatically fix the rate of breathing; as soon as the lungs are filled the apparatus of its own accord marks the moment for ‘deflation,’ and as soon as they are emptied of ‘inflation.’ This automatic reversal is effected by a little bellows which is connected with the air tubes. During inflation the same pressure is exerted in the bellows as in the lungs. As soon as the lungs are filled, the pressure in the bellows increases and it expands, its forward movement causing the reversal to deflation. When the lungs are emptied the bellows contracts, and through this contraction results the reversal to inflation. If, in an exceptional case, the breathing for some reason does not act automatically, the hand of the helper can manipulate it by means of a backward and forward movement of a lever. According to choice, either a nose-mask or a mask covering both mouth and nose can be worn. Combined with the regular apparatus for resuscitation is an ordinary apparatus for the inhalation of oxygen; by the simple altering of a lever, either the one or the other can be employed. II. INDUSTRIAL POISONING IN PARTICULAR INDUSTRIES After the foregoing general remarks we may now consider various points of view in regard to classification of industrial poisonings into groups: (1) Toxicological, based on the action of the poisons. (2) Chemical, based on the chemical composition of the poisons. (3) Physical, based on the varying density of the poisons. (Division into solid (in form of dust), gaseous, and liquid poisons.) To which may be added: (4) Classification according to the source of the poisoning and therefore according to industry, upon which Part I is mainly based. In this section (Part II) a system is adopted which takes into consideration as far as possible all the principles of division mentioned above, in order to classify industrial poisonous substances in such a manner that general practical conclusions can be clearly drawn, and supervision rendered easy. _GROUP: MINERAL ACIDS, HALOGENS, INORGANIC HALOGEN COMPOUNDS, ALKALIS_ Common to this group is a strong corrosive and irritant effect, varying however in degree; as gases this group corrode or inflame the mucous membrane of the respiratory passages, and in liquid form or in solution, the skin. Besides this superficial effect single members of this group, especially those containing nitrogen, produce a remote effect upon the blood.