370 DETECTION OF ADULTERATIONS 



282J to bring out minute crystals that would otherwise escape 

 detection. 



Having studied sections of cinnamon bark in this manner one 

 is prepared to recognize the different tissues in the state of powder. 

 Grind the bark in a perfectly clean mill or with a pestle and pass 

 it by shaking, and not pressure, through the series of fine sieves 

 20, 40, 50, 60, 80, of the U. S. Pharmacopoeia. The bark should 

 be ground to the degree of fineness that results in the same 

 amount of residuum on each sieve as results from an equal weight 

 of the powder whose purity is under investigation. Any frag- 

 ments too large to pass through sieve 50 will need further pul- 

 verization before their cell-elements can well be made out under 

 the microscope. 



The authentic and questionable powders are now to be com- 

 pared under the microscope. Take equal amounts of each pow- 

 der of the same degree of fineness and shake them up in equal 

 small quantities of water 2 parts and glycerine i part; and while 

 still in agitation mount a drop of each of these mixtures under 

 coverglasses of equal sizes. The object is to compare the two 

 powders under as like conditions as possible. 



From both preparations make camera lucida drawings of the 

 different cells and cell-contents as they lie in the field, so that by 

 a comparison of the sizes, shapes, frequencies, etc., of the ele- 

 ments of the two preparations it may be determined whether 

 foreign substances are present in the pow^der under investigation. 



If it proves that the tissue fragments of the powders are too 

 opaque to allow the shapes and sizes of the cells and the thick- 

 ness and markings of the walls to be made out with certainty 

 the powders should be first bleached by the hydrochloric acid 

 and chloral hydrate treatment recommended above for the 

 sections. 



By the above method, while the forms of the cells and the 

 characteristics of their walls are plainly revealed, there may be 

 certain cell-contents, such as some classes of proteids, that will 

 have gone into solution, and the powders should be further com- 

 pared by stirring them up and mounting them in a mixture of 



