DRYING AND PRESERVATION 19 



state in hermetically sealed containers or in well-closed vessels over 

 quicklime. Flowers, kept absolutely dry over quicklime, will retain 

 their natural colours for years and foxglove leaves their constituents 

 unimpaired. 



The second method consists in rendering the enzymes inactive 

 before the drugs are dried. This may be effected by exposing them 

 for a short time to the vapour of alcohol under moderate pressure 

 at a temperature of about 95. Life in the plants is arrested and all 

 the enzymes killed without raising the temperature of the plants above 

 about 80. Fresh kola nuts may be sterilised by exposing them to 

 steam under pressure at a temperature of about 110. By such means 

 the drugs are rendered stable and the process is termed ' stabilisation.' 



Air-dry drugs kept in parcels, sacks, barrels, &c., are liable to be 

 attacked by certain insect pests. Sayre I enumerates about 25. 



The commonest of these insect pests belong either to the Coleoptera 

 (beetles) or Tyroglyphidse (mites). 



Among the Coleoptera the most frequent and most destructive 

 is the drug room bettle (Sitodrepa panicea). This beetle lays its eggs 

 in the summer in crevices in the cork of roots, &c. The young 

 larva drills a tunnel into the drug, hibernates through the winter, 

 passes into the pupa stage in the early summer and finally emerges 

 as a perfect insect about June or July, Dandelion root, burdock 

 root, aconite root, belladonna root, ginger, nutmegs are particularly 

 liable to attack. 



The cigarette beetle (Lasioderma serricorne), the granary beetle 

 (Niptus hololeucus), and Ptinus brunneus also do great damage. 



Among the Tyroglyphidse various species of Tyroglyphus appear 

 to be the commonest. In this case the larva resembles the perfect 

 insect but is smaller and has only six legs instead of eight. It possesses 

 two pairs of strong mandibles with which it tears the drug into small 

 pieces before ingestion. The mites are very minute but they often 

 occur in prodigious numbers. Quince seed, ergot, cantharides, ground 

 linseed and many powdered drugs are liable to be attacked. 



Drugs may be protected from insect pests by keeping them quite 

 dry, or by dusting them with lime which blocks up the breathing 

 apparatus of the mature insect and of the larva. Drugs already 

 infested may be freed from them by exposing them to the vapour 

 of carbon tetrachloride, carbon disulphide, chloroform, &c., by which 

 larvae and mature insects are destroyed. 



Vegetable drugs kept in too damp a place are liable to develop 

 moulds, bacteria, yeasts, &c. These organisms are compelled to 

 obtain part at least of their nourishment from organic substances and 

 in doing so frequently produce ammonia, sulphuretted compounds, 

 &c. The attacks of these organisms may also be warded off by 

 keeping the drugs quite dry. 



1 American Journ. Pharmacy, 1893, p. 321. 



