92 MAPLE-SAP SIRUP. 



The table shows that only three samples examined by the calcium 

 chlorid or association method have a malic acid value below 0.40, 

 about 86 per cent of the total number falling between 0.60 and 1.24. 

 Considering the averages of the individual States, the greatest number 

 lie between 0.80 and 0.99. Jones a states that with a sirup weighing 

 11 pounds to the gallon the malic acid value should not be less than 

 0.40. Calculating this figure to the dry basis gives 0.61, and the data 

 obtained show 43 samples, or 8 .9 per cent, below this limit. The method 

 used in making this determination is somewhat different from that 

 used by Jones, hence the two sets of figures can not be readily com- 

 pared. The amount of ammonia added greatly influences the results 

 and therefore the directions must be carefully and implicitly followed. 



By the Cowles method the results in the individual States do not 

 show such a wide range. Only two samples are below 0.40, and to 

 these may be added 4 samples whose malic acid value lies between 

 0.40 and 0.59. A safe lower limit by this method would be 0.60 on 

 the dry basis. The greatest' number of samples, 73 per cent, have a 

 malic acid value between 0.80 and 1.24. This method gives a solution 

 the precipitate of which readily separates in a short time, and further- 

 more the blanks from the calcium acetate solution are more constant 

 and smaller than those from the calcium chlorid. In most of the 

 work chemically pure chlorid was used that had been recrystallized 

 and dried in order to reduce the size of the blanks'. 



As stated before, the results by the Cowles method average higher 

 than those obtained by the association method. Dividing the results 

 of 480 samples on this basis, it is seen that 29 samples give a higher 

 malic acid value by the association method, in 5 cases they are equal, 

 and on 446 samples the calcium chlorid results are lower. 



Jones states that the results obtained by using calcium chlorid or 

 calcium acetate will be the same if the same amount of ammonia and 

 the same quantity and strength of alcohol are added and there is the 

 same degree of washing. To effect this, he proposes to modify the 

 calcium chlorid method by using one drop of ammonium hydroxid, 

 100 cc of 95 per cent alcohol, heating for thirty minutes, and wash- 

 ing with 85 per cent alcohol to a total volume of 180 cc. In other 

 words, the varying results by the two methods seem to be due to 

 the variation in manipulation and not to the fact that the calcium 

 acetate precipitates all of the malic acid, while the calcium chlorid 

 does not, as is claimed by Cowles. 6 



a Vermont Agr. Exper. Sta., Eighteenth Ann. Kept., 1905, p. 330. 

 b J. Amer. Chem. Soc., 1908, 30 : 1285. 



