148 
From the experiments of Mons. Boulduc*, made on naphtha, 
we learn, that it is so inflammable, that it takes flame before the 
flame which is brought towards it is really in contact with it ; that, 
when heated in a vessel, it inflames by the flame of a candle held at 
a considerable distance above it, a subtile vapour extending some 
feet above the fluid ; and that it will burn freely on the surface of 
water. He also states, that it is so light as to swim on the surface 
of all fluids, even on that of rectified spirits of wine, which is 
heavier than it by one-seventh, and does not manifest any action on 
it. One drop diffused itself over water to more than the space of 
a toise, the water yielding prismatic colours. It mixed perfectly 
with the essential oils, particularly with the oils of turpentine, of 
th^ine, and of lavender. He observed also, that it did not inflame 
on the addition of the concentrated acids, but became thickened on 
their union with them. A piece of paper soaked with it, soon 
became dry, and then, as is the case when spirit of turpentine is 
used, ceased to be transparent. 
By distillation with a gentle heat, du Ble-f, obtained from 
the asphaltum of Neuenberg, a light and limpid oil, which, like 
naphtha, was so subtile, as to evaporate very rapidly in the open 
air; spreading very freely on the surface of water, and taking 
flame very readily. But unlike naphtha, which, according to 
Boulduc, will not unite with alcohol, this essential oil entered into 
union with alcohol with the same facility as oils of lavender and 
turpentine. 
By properly adapted experiments, he also ascertained, that in 
the asphaltum of Neuenberg, both the sulphuric and muriatic acids 
existed, in union with calcareous earth. 
* Histoire I’Academ. Eoyale des Sciences, 1715 p. 15. 
f C. Ludov. I’Agascherie du Ble, Examen Bituminis Neocomensis, 1758. 
