42 FOOD ADULTERATION AND METHODS FOR DETECTION. 



about the proper size and folding it once through the middle and then 

 again at right angles to the first fold. The paper may then be opened 

 without unfolding in such a way that three thicknesses lie together on 

 one side and only one thickness on the other. In this way the paper 

 may be made to fit nicely into the funnel. 



Some additional apparatus, such as test tubes, racks for supporting 

 them, and glass rods, will be found more convenient for one who 

 desires to do considerable work on this subject, but can be dispensed 

 with. The most convenient size for test tubes is a diameter of from 

 one-half to five-eighths inch and a length of from 5 to 6 inches. A 

 graduated cylinder will also be found very convenient. If this is 

 graduated according to the metric system, a cylinder containing about 

 100 cc will be found to be convenient; if the English liquid measure 

 is used it may be graduated to from 3 to 8 ounces. 



CHEMICAL REAGENTS. 



The word " reagent" is applied to "any substance used to eifect 

 chemical change in another substance for the purpose of identifying 

 its component parts or determining its percentage composition." The 

 following reagents are required in the methods here given: 



Turmeric paper. 



Iron alum (crystal or powdered form). 



Hydrochloric acid (muriatic acid) concentrated. 



" CAUTION. All tests in which hydrochloric acid is used should be conducted in glass or 

 earthen ware, for this acid attacks and will injure metallic vessels, such as iron, tin, zinc, 

 etc. Care must also be taken not to bring it into contact with the flesh or clothes. If l>;i 

 accident a drop of it falls upon the clothes, ammonia, or in its absence a solution of saleratus 

 or sal soda (washing soda), in water, should be applied promptly. 



lodin, tincture. 



Potassium permanganate, 1 per cent solution. 



Alcohol (grain alcohol). 



Chloroform. 



Boric acid or borax. 



Ammonia water. 



Halphen's reagent. 



With the exception of the last reagent mentioned, these substances 

 may be obtained in any pharmacy. The Halphen reagent should In- 

 prepared by a druggist rather than by an inexperienced person who 

 desires to use it. This is especially important because of the inflam- 

 mable nature of carbon bisulphid which enters into its composition. 



CAUTION. Carbon bisidphid is a very inflammable substance and is at least as danger- 

 ous to handle as gasoline. For this reason the Halphen reagent, into the composition of 

 n'hii-h carbon bisulphid enters, must be handled with care, and only a small portion of it 

 taken into the vicinity of the fire. When it is employed the end of the test tube may be 

 loosely stoppered n-ltfi mlton. Tin- carbon Insulphid in the amount of reagent used for a 

 single test, hmverer, is so small as not to cause ami fxirtinilar danger in its use. 



