U C. U. C. p. ALUMNI JOURNAL April, 1918 



solution is well diluted, the residue collected on a tared filter, thoroughly dried 

 and weighed. This residue may then be used for microscopical examination. 

 Corn meal, on account of the large amounts of fixed oil contained presents 

 difficulty, but this oil may be removed by a preliminary extraction or less 

 completely by saponification during the alkali treatment. 



Candy, Sugar Products and Chocolate. — The examination of can- 

 dies or sugar products without chocolate coatings is very simple. The separation 

 merely consists in dissolving a given quantity of the sample in water, collecting 

 the insoluble materials upon a tared filter, drying and weighing. The residue 

 should in all cases be examined microscopically as low grade sugars always con- 

 tain considerable fibrous tissue. In the case of chocolate coated confectionery 

 it is advisable to remove the coating and examine the latter separately. Known 

 quantities of the sample are boiled with sodium hydroxide solution (io%) to 

 separate and partially saponify the fat and to remove the starch. While the 

 liquid is hot, decant about three-quarters of the liquid, add a second portion of 

 alkali and boil again. Decant most of the liquid taking care that the .insoluble 

 materials are not lost. Add dilute hydrochloric acid in slight excess and transfer 

 the Uquid to a large separatory funnel containing about loo mils of chloroform. 

 After gentle agitation allow the mixture to stand. Sand, glass or heavy materials 

 will deposit at the bottom of the funnel and may be withdrawn for weighing and 

 microscopical examination. This method gives satisfactory results with bar 

 chocolate. The major portion of the fat may be removed by a preliminary 

 extraction, but this procedure is not absolutely essential and adds to the time 

 required for the analysis. 



Jams, Preserves and Canned Goods. — The most rapid, although not a 

 very accurate method of removing foreign materials from this class of products 

 is by washing through a coarse sieve ( lo mesh). The washings are reduced in 

 bulk by decantation and the remaining liquid with sand or glass transferred to a 

 separatory funnel containing chloroform. The foreign matter will rapidly settle 

 in the funnel and may be drawn off, excess chloroform evaporated and the residue 

 examined microscopically. For accurate quantitative estimations it is advisable 

 to dry and powder the material and then remove the vegetable matter by the 

 action of concentrated sulphuric and nitric acids as described in the paragraph 

 on meats. 



Identification of Residues. 



Where the residue contains or consists of large fragments of glass, positive 

 identification by physical means can be relied upon. Small particles in a residue, 

 especially clear, sharp sand grains may easily be mistaken for minute glass frag- 

 ments and lead to serious errors. The analyst cannot be too careful in the 

 examination of such residues for on his report the question of prosecution for 

 criminal intent may rest. Chemical methods of distinguishing between glass 

 and sand are complicated and time consuming. The method employed by the 



