208 BROOKS. 



Table I. — Analyses of the gases evolved after the first stage of the distillation. 



Number ofdeterrnination. 



Carbon 

 dioxide. 



Unsaturat- 

 ed hydro- 

 carbons. 



Saturated 

 hydro-car- 

 bons and 

 CO. 



1 • 



92.6 

 75.4 

 38.8 

 28.8 

 28.8 







2 



G. 4 

 15.0 

 14.5 

 14.6 



18.2 

 46.2 

 56. 6 

 56.6 



3 



4 



5 . 





The total quantity of carbon dioxide given off during the first stage 

 was determined in another experiment in which this gas was absorbed by 

 a solution of caustic soda. An - aliquot portion of the alkaline solution 

 was acidified in the form of apparatus described by Hillebrand 18 for the 

 determination of carbon dioxide in carbonate rocks, the gas being absorbed 

 in caustic potash and weighed. The amount found corresponded to a 

 total of 48 grams from 1,500 grams of resin, or 3.2 per cent. 



This amount of carbon dioxide is probably given off by the decomposition of a 

 carboxyl group. The resin oil which distills over when the temperature is raised 

 consists largely of neutral oils. One sample of resin oil contained 63 per cent 

 of neutral substance. As has been shown by G. F. Richmond 19 the original resin- 

 ous substance consists almost entirely of compounds of an acid character. The 

 ease with which these resin acids lose carbon dioxide is similar to the behavior 

 of abietic acid, which can not be distilled even in vacuo without the loss of a 

 large percentage of that gas. 



The gases given off during the melting of resins used in varnish making 

 are commonly described as having an irritating odor, but are not gener- 

 ally considered as being dangerous. 



Baehem 2 ° recently recorded a case of fatal poisoning by the gases from a 

 melting kettle in a varnish factory. He analyzed the gases given off by colophony 

 and found carbon monoxide in amounts varying from 10.6 to 39.0 per cent. 



The amount of carbon monoxide given off by Manila copal was quan- 

 titatively determined by absorbing the gas in cuprous chloride, in the 

 usual manner, care being taken that the unsaturated hydrocarbons were 

 previously removed by strongly fuming sulphuric acid. Two samples, 

 taken at different stages, showed 11.4 and 15.5 of carbon monoxide. The 

 presence of this gas was also shown by killing two white rats with small 

 amounts and examining the absorption spectra of samples of their blood 

 before and after the addition of a few drops of ammonium sulphide. 

 Considering the rather large amounts of carbon monoxide found in the 

 gases, it is surprising that their toxicity has not been more often noted 

 by varnish manufacturers, or their workmen. 



18 £7. S. Geol. Surv. (1907), Bull. No. 305, 151. 



19 This Journal, Sec. A. (1910), 5, 187. 

 ■"Arch. f. exp. Path. u. Pharm. (1907), 57, 222. 



