DRUGS WHICH ACT ON THE LUNGS 471 



variety of ways, it may be said that their chief and most general action 

 is to stimulate the circulation of the blood in the lining membranes of 

 the air-tubes and produce an increased secretion. Inhaling the vapour of 

 hot water is one of the most simple and effective means of producing this 

 desirable action, and medicaments of various kinds are frequently added. 

 Of these may be mentioned the balsams of Peru and Tolu, copaiba 

 and storax, camphor, myrrh, benzoin, and other volatile drugs, while for 

 certain specific diseases agents are prescribed for inhalation for their anti- 

 septic and other qualities rather than as pure stimulants or expectorants. 

 Among this class, carbolic acid, turpentine, tar, eucalyptus, and other 

 essential oils play an important part in the treatment of disease. Special 

 apparatus is now made for giving inhalations, but in its absence the 

 nose-bag may be made to do duty, with some hot bran and scalded hay, 

 care, however, being taken not to scald the muzzle of the patient, as too 

 frequently happens. 



REMEDIES WHICH SOOTHE THE LUNGS AND AIR-PASSAGES 



Reduction of the volume of blood circulating in the lungs is the most 

 certain means of reducing their irritability, and a determination of blood 

 to a particular part is combated by remedies which create a diversion from 

 what are commonly called vital centres to the skin or subcutaneous tissues; 

 hence the use of poultices and fomentations, warm liniments, and still 

 more active vesicants, as mustard. The internal application of heat to the 

 air-passages is afforded by the inhalation of steam, and the effect is to cause 

 dilatation of the air-passages, more particularly of those with which contact 

 is most direct. The effect of saline and other aperients is also soothing 

 to the lungs for the same reason that a diversion of blood to the bowels 

 relieves the pressure in the respiratory system. Another means of soothing 

 the air-passages and reducing circulation of blood in the lungs is rest from 

 all muscular exertion. It is noticeable in horses how cough is excited by 

 movement and allayed by repose. 



The circulation may also be lessened by such drugs as aconite, anti- 

 mony, and ipecacuanha. 



REMEDIES WHICH REDUCE EXPECTORATION 



Removal of the cause of, or allaying, the irritability of the air-passages 

 is to be desired, and the treatment for respiratory troubles is more gener- 

 ally dealt with under the heading of pulmonary diseases. It is, however, 

 found that acid tonics in combination with such soothing agents as bella- 

 donna, hyoscyamus, camphor, and opium have the effect of reducing the 



