6SG ANNUAL REPORTS OP THE DEPARTMENT OF AGRICULTURE. 



made use of in labeling cheese from which two-thirds or three-fourths 

 of the fat had been removed from the milk at the time of manufac- 

 ture of the cheese. In other cases " part skims " were sold as " full 

 creams," or simply as "cheese," Avhich is the same thing. 



The sale of bulk condensed milk, both sweetened and unsweetened, 

 that has been skimmed or parity skimmed for genuine condensed 

 milk is still a more or less common practice. 



Violations of the law in the butter trade consist mostly of the sale 

 of butter containing an excessive amount of water, the substitution of 

 t)leomargarin for butter, and sometimes the sale of short-weight but- 

 ter in pound i^rints. 



A classified list of the cases prepared by this laboratory is as fol- 

 lows : 



Milks and creams 157 



Cheese Gl 



Evaporated milks o2 



Ice creams ;; 



Sweetened condensed milks ];; 



Butter k; 



Total 2S2 



Of these 114 were prepared from analyses made in the branch 

 laboratories of fresh milks, condensed milks, cheese, and butter. As 

 usual, work has been done in the study of methods for the analysis of 

 dairy products. 



The decrease in the nmtiber of samples examined during the 

 year is accounted for in a great measure by the small laboratory force 

 for more than one-third of the year, due to two resignations. 



SPECIAL INVESTIGATIONS. 

 PHYSICAL CHEMISTRY. 



During the past year the study of an improA'ed method for esti- 

 mating sugar in foods and drugs by the use of the enzym invertase 

 has been continued, with good results. A large number of analyses 

 and measurements have been made, and the use of invertase, which 

 was favorably commented upon in the last report, has proved to be 

 the best method for determining sugar in these products. A study 

 of the occurrence of cane sugar in honey, in which invertase was 

 used for the estimation, has shown that the amount of sugar in gen- 

 uine honeys is considerably lower than has been heretofore sup- 

 posed. Other studies included the chemical properties of the sugar 

 rafRnose, which occurs in many foods and drugs, a method for ob- 

 taining this sugar from cottonseed meal, and a method for estimat- 

 ing maltose and lactose in foods and drugs. 



In March a study of the physical and chemical problems involved 

 in the commercial manufacture of candy Avas begun and is now in 

 progress. The causes for the aging of candy, which in some cases 

 involves chemical changes producing rancidity and in others only 

 physical changes, such as granulation of the sugar and hardening of 

 the candy, are being investigated, as well as the influence of glucose, 

 invert sugar, and like substances upon the character and keeping 

 qualities of all of the common types of candy. 



