52 Browning — Method for the Quantitative 



were removed from the beaker by washing with small amounts 

 of previously boiled amyl alcohol contained in a wash-bottle 

 the mouthpiece of which consisted of a small chloride of cal- 

 cium tube passing through the stopper and drawn out and 

 plugged at the lower end with cotton to exclude particles of 

 the calcium salt from the alcohol. By this device the intro- 

 duction of moisture into the amyl alcohol was guarded against. 

 The crucible containing the strontium nitrate was placed in an 

 air bath and heated to 150° C. to drive off all amyl alcohol, 

 and weighed. A constant weight was obtained uniformly in 

 one treatment. Series I contains the results of these experi- 

 ments, the strontium being calculated as oxide. 



Series I. 



(1) SrO taken 0-1229 grm. SrO found 0-1220 grm. Loss 0-0009 grm. 



(2) " " 0-1231 " " " 0-1221 " " 0-0010 " 



(3) " " 0-1230 " " " 0-1219 " " 0-0011 " 



(4) " " 0-1227 " " " 0-1213 " " 0-0014 " 



These results suggested a possible solubility of the stron- 

 tium salt, and, accordingly, experiments were made to test this 

 point. Amounts of strontium nitrate closely agreeing with 

 those above were taken and treated in the same manner. The 

 filtrates amounting, without the washings, to about 25 cm 3 

 were evaporated to dryness. The residue was ignited to burn off 

 organic matter from the amyl alcohol, treated with sulphuric 

 acid, heated to low redness, and weighed. In two cases the resi- 

 due of strontium sulphate was found to contain of the oxide re- 

 spectively O0009 grm. and O0010 grm. As will be seen the 

 solubility of the strontium nitrate averages about OOOIO grm. 

 of- the oxide to 30 cm 3 of amyl alcohol used. The exact 

 extent of this solubility depends, of course, upon the amount 

 of amyl alcohol remaining after boiling ; and, since the source 

 of heat is removed as soon as the normal boiling temperature 

 of the alcohol is reached, very little decrease in the volume of 

 the previously boiled alcohol results. On measuring the 

 amounts of the alcohol remaining in several experiments I 

 found them to approximate closely to 25 cm 3 . It seemed justi- 

 fiable, therefore, to add as a correction to the apparent amount 

 of strontium oxide found 0*0010 grm. for every 25 cm. 3 of 

 amyl alcohol remaining, or for every 30 cm. 3 originally taken. 

 Experiments were also made to determine whether the stron- 

 tium nitrate might have been at all broken down in the process 

 of boiling and heating so that some strontium might be present 

 in the final residue in the form of oxide or nitrite. In two 

 of these experiments portions of strontium nitrate left by the 

 treatment with amyl alcohol were dissolved, precipitated as the 



