632 PHILOSOPHICAl. TRANSACTIONS. [aNNO 1742-3. 



only reach the ground, the greater part adhering to the bark of the tree. Be- 

 sides, amber is often found on mountains, and in pits, where trees were never 

 planted. And as to the arguments from the distillation of vitriolic acid with 

 turpentine, they do not prove the case ; for though something bituminous is 

 then produced, it is not real amber, as it wants the equal mixture, transparence, 

 elasticity, and hardness. This may be easily and quickly produced, by the 

 mixture of any distilled ethereal oil, coagulated with vitriolic acid ; from 

 which mixture there presently arises something bituminous, but not amber. 



Amber probably derives its origin from a mineral, viz. from a soft bitumen 

 (oleum naphtae) and a sulphureous vitriolic acid, which mix in the form of steam, 

 and presently harden. — This is also proved by the fossil amber; for wherever 

 this is dug up, there are also found, among the' blue clay, bituminous wood, 

 coal, vitriol, and often alum. And the amber found in the sea, is produced in 

 the same manner as that formed in the mountains, being only washed out of the 

 earth by the beating of the waves, and partly lost in the deep, partly thrown up 

 on the banks. 



Further, as the vitriolic acid, with the bitumen, produces the form and 

 semblance of amber; that acid will quite dissolve it again, and leave it in the 

 same state, without destroying any constituent part, reducing its hardness, 

 transparence, and elasticity. 



An Account* of a Booh intitled, A Treatise of Fluxions, in Two Books. By 

 Colin Maclaurin, A. M., F. R. S. 2 Fols. Ato. N" 468, p. 325. 



The author's first design, in composing this treatise, was to establish the 

 method of fluxions on principles equally evident and unexceptionable with those 

 of the ancient geometricians, by demonstrations deduced after their manner, in 

 the most rigid form, and by illustrating the more abstruse parts of the doctrine, 

 to vindicate it from the imputation of uncertainty or obscurity. But he has 

 likewise comprehended in this work the application of fluxions to the most im- 

 portant geometrical and philosophical inquiries. It consists of an introduction, 

 and two books. In the introduction he gives an abstract of the discoveries of 

 the ancients in the higher parts of geometry, with observations on their method, 

 and those that first succeeded to it. The first book treats of fluxions in a geo- 

 metrical method, and the second treats of the computations. 



In the introduction we have an abstract not only of the discoveries of the 

 ancients in the higher parts of geometry, but likewise of their demonstrations. 

 After an account of the propositions of this kind, that are to be found in the 



• This very able and masterly account was probably the composition of the excellent author 

 himself. 



