I/o 



Sanitary Studies of Baking Powders 



and Hoagland^ (see later) and showed no aluminum in the dog 

 or ox blood used in this work. The results are given in Table 4. 



TABLE 4 



Data pertaining to the determination of aluminum in blood by Steel's method 



The low results shown in the above table conclusively prove the 

 unreliability of the method. 



Method of Schmidt and Hoagland.° "The vol. at this point 

 should be about 300 cc. and contain about 2.5 cc. of conc. HCl. Di- 

 ammonium hydrogen phosphate is added to the sei. — 0.5 gm. for each 

 100 mg. of AIPO4 present. The sol. is heated, and while hot 5 gm. of 

 (NH4)„S203 (in sol.) and after several minutes 6-8 gm. of 

 NH4C2H3O2 (in sol.) and 4 cc. of strong acetic acid are added. Heat- 

 ing is continued for about J^ hr. to expel SO2, the precipitate allowed 

 to settle, filtered, and washed once by decantation. The precipitate is 

 redissolved in 2-2.5 cc of conc. HCl, the sol. diluted to 300 cc, 0.5 gm, 

 of (NH4)2HP04 added for each 100 mg. of AIPO4 present and the 

 aluminium ag^in precipitated as described above. The precipitate is 

 filtered and washed several times with hot water to remove Chlorides 

 and ignited in a transparent silica crucible, until constant weight is 

 reached, to remove excess of P2O5." 



The above method was followed exactly. Silica crucibles were 

 used for the ignition of the AIPO4. The results obtained with pure 

 mixtures of iron and aluminum are given in Table 5 and leave noth- 

 ing to be desired. 



The filtrations are extremely rapid and the ignitions proceed 

 very smoothly, requiring no special precautions. 



8 Schmidt and Hoagland : Lac. cit. 

 •> Schmidt and Hoagland : Loc. cit. 



