1819.] 



Scientific Intelligence. 



387 



RAIN. 



XIV. Method of preserving Water at Sea. 



M. Perinet, who has examined the different methods recom- 

 mended for preventing water from becoming putrid at sea, 

 considers the following as the best : He mixes black oxide of 

 manganese with the water to be preserved in the proportion of 

 li of the former for every 250 parts of the water, and shakes 

 this mixture once a fortnight. Black oxide of manganese has 

 not merely the property of preventing water from becoming 

 putrid ; but M. Gay-Lussac informs us, that it sweetens water 

 already putrid ; but unfortunately the water retains a little of the 

 oxide in solution (Ann. de Chim. etde Phys.xi. 110). I presume 

 that this portion will be precipitated when the water is boiled. 

 It is probably held in solution by sulphuretted hydrogen ; unless 

 indeed it has the property of converting sulphuretted hydrogen 

 into sulphuric acid," which is not improbable, though it has not 

 been determined by experiment. 



XV. New Method of preparing Pharmaceutical Extracts. 

 By John T. Barry, Esq. 



Mr. Barry's method consists in completing the evaporation of 

 vegetable juices and infusions in vacuo by means of a simple appa- 

 ratus which he has contrived for the purpose, and for which he has 

 obtained a patent. By this mode of operating they are excluded 

 from the action of the air, and at the same time the necessity 

 of exposing them to a higher temperature than from 90° to 100° 

 is superseded — two most important points in the preparation of 

 this class of medicines. Extracts thus prepared differ from those 

 in common use, not only in their physical, but their medicinal 

 properties. Thus " the taste and smell of the extract of hem- 



2 b2 



