METHODS OF ANALYSIS USED. 



21 



the samples two sets of results are given. They show that while some 

 have undergone no alteration even after 18 months others have con- 

 tinued to change. All of the figures on the latter samples are of 

 interest as indicative of the changes which may take place in turpen- 

 tines during aging. The results on the turpentines which had evi- 

 dently changed greatly were not considered in forming a judgment 

 regarding the individual constants of turpentine. 



The following summary of the analytical data on unadulterated 

 turpentines, based on the detailed figures given in Tables I and II, 

 shows the extremes obtained: 



Summary of analytical data on unadulterated turpentines. 



In setting these limits the results on several samples have been 

 ignored, because there was doubt as to the purity of the sample, or 

 as to the exactness of the results. 



The summarized data show that turpentines which are unadul- 

 terated, in the sense that they have had nothing added to or taken 

 from them, give widely different results when analyzed under the 

 usual conditions. Thus unadulterated turpentine may begin to 

 distill, under the conditions obtaining in this work, at from 154.5 to 

 159 C. The amount distilled below 160 C. varies from 42 to 94 

 per cent, below 165 from 69 to 99 per cent, and below 170 from 77 

 to 99 per cent. The specific gravity ranges from 0.8617 to 0.8989 at 

 20 C. and the refractive index from 1.4684 to 1.4818. The residue 

 on polymerization with 38 normal sulphuric acid ranges from 0.2 to 

 1.0 per cent, and the refractive index of this residue at 20 C. may be 

 as high as 1.5200 but should never be below 1.500. These differences 

 are due to natural variations in the freshly distilled turpentine, to 

 aging, and to variations in conditions of analysis. 



It should be borne in mind that many samples of old turpentine are 

 undoubtedly represented in this lot, as well as turpentines stored in 

 wood and in metal, and in clean containers as well as in tanks which 

 still held the residues of previous purchases. In other words, the 

 samples fairly represent those .found on the wholesale and retail 

 market at any time. Certain of these samples can not be properly 

 termed turpentine because they do not possess the constants of 

 turpentine. 



