18 BULLETIN 377, U. S. DEPARTMENT OF AGRICULTURE. 



The preparation finally proposed by Dr. Cross is made as follows : 



Prepare a sirup: 



Granulated sugar pounds 15 



Water pints 7 



Tartaric acid (crystallized) 1 ounce i 



Boil for 30 minutes. Allow to cool. 



Dissolve sodium arsenite (C. P.) ounce__ I 



In hot water pint 1 



Cool.* Add poison solution to sirup and stir well. Add to the 

 poisoned sirup: 



Honey pounds 1J 



Mix thoroughly. 



On April 23, 1914, Dr. Cross and the writer prepared two sirups of 

 the above formula (exclusive of the honey, which only makes the 

 sirup more palatable) , except that one lacked the tartaric acid. After 

 cooling, they were tested in a refractometer, with the following 

 results : 



Sirup with tartaric acid, specific gravity 1.339, Brix (sugar content) 68.8. 

 Sirup without tartartic acid (Nickels sirup), specific gravity 1.343, Brix 68.05. 



The Nickels sirup had lost 0.75 per cent of its sugar content and 

 was of a very dark brown color. The new sirup w r as bright yellow 

 (amber color), clear, and transparent. Equal samples of each were 

 placed in quart exhibit jars w r ith ground-glass stoppers, labeled, and 

 set aside. A second reading was made on June 20, 1914, as follows: 



Sirup with tartaric acid, specific gravity 1.340, Brix 68.40. 

 Nickels sirup, specific gravity 1.3321, Brix 67.01. 



The new sirup had lost 0.4 per cent of its total solids and had not 

 noticeably changed in color or sweetness. The Nickels sirup had lost 

 1.04 per cent of its total solids, w r as nearly black, partly crystallized, 

 and had lost much of its sweetness. In the beginning of August the 

 stoppers were removed and cheesecloth tied over the mouths of both 

 jars, to find how evaporation would affect these sirups. The jars 

 were placed on a shelf in the laboratory. In the beginning of 

 January, five months after the jars were first left open, they were 

 examined. Figure 2 shows the conditions. The difference in the 

 quantity of the sirups, in color, and in the crystallization that had 

 taken place within the jar containing the Nickels sirup may readily 

 be noted. A reading was taken of these sirups, as follows : 



Sirup with tartaric acid, specific gravity 1.385, Brix 75.48. 

 Nickels sirup, 1.367, Brix 72.68. ' 



1 In the first experiments one-half ounce of tartaric acid was used, hut this is found 

 unnecessary. 



2 In earlier experiments the sirup was boiled 30 minutes after addition of the poison, 

 but boiling will raise the " Brix " (total solids), which is to the disadvantage of the sirup 

 as an ant bait. 



