USES OF GELATINE AND GLUE 261 



unpleasantness. In making these capsules some sugar is 

 also used, and the finished article is often protected from 

 atmospheric moisture by treatment with a weak solution 

 of alum. In a similar way pills are often coated with a 

 33 per cent, gelatine sol. Such pills are not only pleasanter 

 to swallow, but are less liable, after being dried, to stick 

 together in the box. Acohol solutions of drugs (or essences, 

 perfumes, etc.) may be suitably stored in gelatine instead 

 of metal tubes. Medicated wines are detannated by 

 gelatine before the addition of drugs which would have 

 been precipitated by the tannin. The British Pharma- 

 copoeia specifies four kinds of " Lamellae, " which are 

 small discs of gelatin and glycerin, each containing a minute 

 but definite dose of some powerful alkaloid. Glycerin 

 jelly is a mixture of gelatin glycerin with some water. 

 It is used for chapped and rough hands ; the mixture is 

 also used for glycerin suppositories, and for mounting micro- 

 scopic sections. The mixture also forms the basis of gelato- 

 glycerin, used in nasal bougies, and of glyco-gelatin for 

 medicated lozenges. Gelatine insolubilised by formalin 

 (formo-gelatin) has been used for making tabloids, wound 

 dressings, and artificial silk. 



Gelatine is in constant demand for bacteriological work, 

 for which purpose a high-grade product is desired. Nutrient 

 media for the culture of bacteria are solidified by 10-15 per 

 <vnt. of gelatin, and the growth of colonies of bacteria often 

 show typical formations. By inoculating into a melted 

 and sterile quantity and setting quickly in a flat dish after 

 mixing, the number of bacteria in the volume introduced 

 can be judged from the number of colonies which develop. 

 Bacteria are also distinguished often as " liquefying " or 

 "non-liquefying" according to their type of culture on 

 nutrient gelatine media. Gelatine for such work should be 

 liCUtral and of hiiji clarity. 



The gelatine required for photographic purposes is also 

 a high-class product. It should be neutral, colourless, and 

 free from chlorides ;m<l other mineral salts. Grease also is 

 objectionable Gelatine is used in the numerous carbon 



