100 ODOROGRAPHIA. 



The small proportion of chloride here shown would justify the 

 assumption that the chloride of lime process had not been 

 employed. Moreover, on two out of three samples containing 

 calcium carbonate, small particles of ultramarine blue were 

 detected ; and this, under the name of " lime-blue," is commonly 

 used to imx^rove the colour of lime washes. From these facts it 

 would appear that three of the samples had been simply white- 

 washed, without any attempt at bleaching, and then dusted over 

 with plaster of Paris. 



Powdered ginger is adulterated with sago-meal, potato-flour, 

 wheat-flour, ground-rice, cayenne pepper, mustard husks, and 

 turmeric powder and various amylaceous substances blended in 

 varying proportions. These adulterations are readily detected by 

 the microscope, except in the case of the East Indian arro\v-root 

 {curcuma angustifolia) the particles of which are similar in 

 appearance to those of ginger. 



A very elaborate study of the constituents of ginger was made 

 by Thresh, and formed the subject of a paper read at the British 

 Pharmaceutical Conference in 1879.* 



A partial investigation of oil of ginger was made by the same 

 scientist, and was also read as a paper at the Conference of 188 l.f 

 In this last paper it is stated that the proportion of essential oil 

 obtained from a sample of Jamaica ginger amounted to 1-4 per 

 cent. The yield of oil from various gingers has been noticed by 

 other observers:]: to be from 1-9 to 2-7 per cent, having a sp. gr. at 

 15° C. of 0-880 to 0-885, and an optical rotation of— 25° to— 40° 

 in a 100 m. m. tube. The chemical composition of ginger oil 

 remains unknown, but the presence in it of camphene and 

 phellandrene have been detected. § The complex nature of the oil 

 is indicated by the wide range of its boiling point ; the results 

 obtained by Thresh, on fractionating, are recorded as follows : — 

 " When distilled after drying over Ca CU the oil begins to pass 

 over at about 140° C, accompanied by a few drops of aqueous 

 fluid. The temperature constantly and rapidly rises to about 

 240°, the chief portion of the oil coming over between 240° and 



* lieprinted in Pharra. Journ. [3], x. pp. 171 and 191. 

 t lieprinted in Pharm. Journ. ['-{J, xii. p. 243, 

 X Schimmers Pveport, October, 1893. 

 § Ibid, p. 25. 



