592 FOURTH REPORT — 1834. 



aspect of gold. It is not volatile when pure. It is easily fixed 

 on cloth, and forms a permanent dye of remarkable beauty. 



5. Picamar. — This is the bitter principle produced in de- 

 structive distillation. It is an oily liquid, heavier than water, 

 boiling at a temperature above 500° Fahr. It is vei'y perma- 

 nent. It has an intensely bitter taste. From its permanence 

 and fixity, it is well adapted for greasing machinery. 



6. Kapnomor. — This is a liquid, sp. gr.0'977, boiling at SGo"^ 

 Fahr. Its most important property is its power of dissolving 

 caoutchouc. It forms the chief part of the coal naphtha em- 

 ployed in the arts. 



Besides these new substances, Dr. Reichenbach has recog- 

 nised acetic acid, pyroligneous and pyroacetic spirits, in the 

 products of destructive distillation. He considers, and appa- 

 rently with good reason, the pyroligneous spirit as a mixture 

 of alcohol with pyroacetic spirit. The alcohol is formed by the 

 fermentation of sugar in the sap of the wood, and distils over 

 when heat is applied to the wood. Naphthaline is not, accord- 

 ing to Dr. Reichenbach, a product of destructive distillation, 

 properly so called, but is always formed when any of the pro- 

 ducts above mentioned are exposed, in the state of vapour, to a 

 red heat. 



Dr. Reichenbach has also shown that the naphtha distilled 

 from the Italian and Persian petroleum, is not produced by 

 destructive distillation, but is oil of turpentine unaltered, the 

 origin of which he attributes to the pine-forests of which most 

 coal beds are composed. Some very fine naphtha, sent by 

 Mr. Swinton from the East Indies, was found by Dr. Christison 

 to have all the characters of oil of turpentine. Dr. Christison 

 supposed that this oil had been fraudulently substituted for the 

 naphtha, but Dr. Reichenbach has succeeded in obtaining a 

 similar oil from several species of coal, by distilling along with 

 water, in which case no destructive distillation could occur. 



One naphtha, however, from Rangoon, appears to be a pro- 

 duct of destructive distillation. Dr. Christison discovered in 

 it paraffin, which he called petroline, Dr. Reichenbach's expe- 

 riments not being at that time known in this country ; and 

 Dr. Gregory has lately proved in it the presence both of 

 eupion and kapnomor. There is reason to think, therefore, 

 that this naphtha, and perhaps some others, have been pro- 

 duced at a high temperature. 



