136 Mr, Chamberlain on Napthalhie, [AtG. 



sometimes become actually solid, when it has been a few hours 

 distilled. The quantity of napthaline usually obtained is proba- 

 bly about five pounds from 100 gallons of the coal tar ; but if 

 the distillation be hurried towards the middle or latter end of 

 the operation, the quantity of napthaline is much increased : 

 may not this happen from the conversion of the oil into naptha- 

 line by the increase of temperature? The last portion of 

 napthaline obtained is mixed with a very large quantity of 

 sulphur. 



If sulphuric acid be added to coal tar, little or no napthaline 

 is procured ; the acid probably decomposes the napthaline, for 

 it nolds but a very small quantity of it in solution. 



When spirit or oil of tar obtained in making pitch, is set aside, 

 much napthaline separates from it in a few weeks ; and this effect 

 may be more quickly produced by artificial cold ; but agitation 

 or increase of temperature readily dissolves the portion so depo- 

 sited. 



The napthaline is deposited from the oil in the vessels which 

 contain it, in a semi-crystalline state, and much resembling 

 coral in appearance, excepting that it is greyish instead of being 

 perfectly white ; by keeping, it becomes of so very dark a brown 

 colour as to be nearly black ; when large masses of it are broken 

 the structure is frequently crystalline at the centre. 



The smell of napthaline is extremely powerful and peculiar ; 

 when melted and allowed to cool gradually, it presents cells 

 ■which are intersected in every direction by beautifully white and 

 shining plates. 



The napthaline separated from oil which has been twice dis- 

 tilled, requires a much greater heat to sublime it than that 

 found originally in the oil ; the latter melts at about 120°, and 

 begins immediately to sublime ; but if sulphuric acid be tritu- 

 rated with it, it requires a greater heat even than the first men- 

 tioned for sublimation ; and by this process, there is obtained a 

 mass resembhng a honeycomb in appearance, owing to the pecu- 

 liar arrangement of the crystalline napthaline. 



During the sublimation of napthaline, a fluid is obtained 

 which is worthy of careful examination. At first its taste is 

 i^eety and highly aromatic ; it is afterwards pungent ; and occa- 

 sionally hydrocyanic acid may be obtained from it, and in 

 pretty considerable quantity. 



When napthaline is mixed with water, it rises in vapour with 

 the water ; m this way it is obtained in a state of greater purity 

 than by sublimation, but the quantity procured is small. Nap- 

 thaline is soluble in spirit of wine, and by evaporation ciystals 

 are obtained, but they are neither large nor perfect ; nor when 

 dissolved in oil of tar, can any distinct crystals be obtained ; 

 after trying various fluids for the purpose of procuring perfect 

 crystals, 1 succeeded but with oil of turpentine. 



