88 Chemijirr. 



that ens veneris is fal ammoniac, coloured by an oxyd of 

 copper: but I can eafily prove that the one confifts offal 

 ammoniac and tiie muriat of iron, and the other of fal am- 

 moniac and the muriat of copper. 



ift, When iron or copper is added to fal ammoniac, the 

 fait is decompofed, the iron or copper unites to the muriatic 

 acid and forms a muriat of iron or copper, which, when ex- 

 pofed to heat in clofe vellcls, fublimes with the fal annno- 

 niac, while the volatile alkali is fet at liberty. 



2dly, Flores martiales, or ens veneris, may be made by 

 fubliming fal ammoniac with the muriat of iron or copper, 

 prepared by adding the muriatic acid to thefe metals. 



^dlv, When fibres martiales, or ens veneris, are dilTolved 

 in water, and luflbred to crvrtallife, the muriat of iron and 

 copper will be obtained feparate from the fal anmioniac. 



6. Of Aromatic Oils, ohfained from the Pellicle ivhich 

 envelops the Seeds of the Lanrus Sajjufras and Laurus 

 Benzoi7i. 



The method of obtaining thefe oils is, to boil the pclhcle 

 which furrounds the feeds of the faflafras and bcnjarnin-trec 

 in water ; when they float upon its furface, from which thev 

 may be fkimmed with a fpoon. 



That of the faflafras differs materially from the oil ob- 

 tained from the bark of the root of this tree. Its aroma is 

 different ; it is much lighter, and it congeals in a higher de- 

 gree of heat. 



The oil of the benzoin-tree is a delightful aromatic, is 

 very inflammable, and might be ufed as a fpice in food, and 

 in all thofe difeafes in which the aromatic oils are ufeful. It 

 has been tried with fuccefs, as an external apphcation," in a 

 fevere cafe of chronic rheumatifm. One half pound of the 

 pellicle of the feeds will yield feveral ou,nce meafures of oil. 



7. Of the JEiidiometer. 



The eudiometer is an ufelefs iuftrument in afccrtaining the 

 puiiiy of atni jfpheric air. 



jfl. Be- 



