DAIRY PRODUCTS. 107 



In the present state of our knowledge, therefore, the specific rotatory 

 wer of milk sugar should be taken at (a) v = 52.5. 1 propose, at an 

 ly date, to make a careful study of this subject, in order to fix, it' 

 sible, an exact number for the expression of the rotating power, 

 and to examine the conflicting evidence respecting the influence of the 

 degree of concentration on the same. The estimation of lactose in 

 milk by the polariscope is rendered difficult also by the presence in 

 milk of various albumens all of which turn the plane of polarization 

 to the left. As will be seen by the data given further along, the ordi- 

 nary method of removing these albumens, viz, by a solution of basic 

 lead acetate, is far from being perfect. If, therefore, a portion of the 

 albumen be left in the liquid submitted to polarization, the rotation to 

 the right will be diminished by its presence. 



Hoppe-Seyler 1 assigns as the rotation power of egg albumen () 

 = 35.5, and for serum albumen (^) n = 56. Both acids and alka- 

 lies seem to increase the rotating power, which may with acetic acid reach 



() = - 71. 



Fredericq 2 gives the rotation number for blood serum for the rabbit, 

 cow, and horse at (a) u = 57.3, and for the dog at 44. Para-globulin, 

 according to the same author, has a rotation number ()= 47.8. 



Milk albumen 3 has the following numbers assigned to it : 



Dissolved in Mg. SO 4 sol. (a)n= - 80 



Dissolved in dil. HC1. (a) n = 87 



Dissolved in dil. NaOH sol. ()=- 76 

 Dissolved in strong KOH sol. (a)i>~ 91 



The hydrates of albumen 4 have rotation powers which vary from 

 .(a),, =71.40 to (a) u = 79.05. From the chaotic state of knowledge 

 concerning the specific rotating power of the various albumens, it is im- 

 possible to assign any number which will bear the test of criticism. 

 For the purposes of this report, however, this number may be fixed at 

 (>)= 70 for the albumens which remain in solution in the liquids po- 

 larized for milk sugar. 



The phenomenon of "birotation" in milk sugar has already been 

 noticed. The problem of analysis of this sugar is, however, still fur- 

 ther complicated by the facts pointed out by Schmoeger 5 and Erdmanu," 

 that when milk is rapidly evaporated in a plain dish the sugar is left 

 in the anhydrous state, and that this sugar in fresh solutions exhibits 

 the phenomenon of " half rotation." When such sugar is extracted 

 with alcohol and re-evaporated, it, doubtless, is still anhydrous. But 

 in the calculation of results this sugar is generally estimated as con- 

 taining water of crystallization, and thus an error, which Schmoeger 

 ^b as much as .2 per cent., is introduced into the results. This 

 Ptirtz, Diet, do Chiniio, vol. 1, 1st part, p. 91. 

 !oinpt. Rend., vol. 93, p. 465. 

 -loppe-Soyler iu Handbook of the Polariscopo, Landolt, p. 248. 

 1 Kiilino. and (Jliittonden, Am. Cliom. Jour. vol. 6, p. 45. 

 ' Her. diem. (Jesoll, vol. 12, 1915 ct *eq.; vol. 13, p. 212 ct scq. 

 ' F.or. diem. Ge.soll., vol. 12, p. '2180 et scq. 



f\ 



