142 i\Ir. J. D. Smith on Early Egyptian Chemistry. 



fact of this equivalence is, as I have stated, deduced from that 

 remarkable but simple law to which I have adverted, which 

 affirms the invariability of the number of the positive and nega- 

 tive signs between all linearly equivalent functions of the form 

 S + Cj. . x^ (subject, of course, to the condition that the equivalence 

 is expressible by means of equations into which only real quan- 

 tities enter) ; a law to which my view of the physical meaning 

 of quantity of matter inclines me, upon the ground of analogy, 

 to give the name of the Law of Inertia for Quadratic Forms, as 

 expressing the fact of the existence of an invariable number in- 

 separably attached to such forms. 



26 Lincoln's-Inn-Fields, 

 July 12, 1852. 



XX. Early Egyptian Chemistry. By J. Denham Smith. 

 To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 



PERIMIT me to occupy a small space in your Journal with a 

 few observations on Mr. Herapath's paper with the above 

 title, published in your Supplement Number for July. 



Mr. Herapath's fact of a solution of silver having been used 

 some three thousand years since as " marking-ink,'^ is in every 

 way interesting, being excellent additional evidence of the fami- 

 harity of the ancient Egyptians with a somewhat advanced stage 

 of the chemical arts ; but dissenting as I do from all the deduc- 

 tions Mr. Herapath has arrived at from this fact, and thinking 

 it probable that they may take deep root and become widely 

 spread as received opinions, if unremarked upon, I have ventured 

 to allege a few reasons in refutation of the inferences of yom- 

 correspondent. 



The first conclusion necessarily involved in the views of Mr. 

 Herapath is, that the ancient Egyptians must have been ac- 

 quainted with nitric acid ; the second is, that they were familiar 

 with the use of sulphuiic and hydrochloric acids ; the third, 

 that the Great Lawgiver travelled with what must be considered 

 a well-appointed laboratory, or, which is still less probable, was 

 able to construct an impromptu one (both matei'ials and appa- 

 ratus) in the Desert ; and the fourth, that the golden calf was 

 dissolved in aqua regia ; all of which conclusions are founded 

 and built up on the single fact of the existence on mummy linen 

 of marks which must have been produced by a solution of silver. 



To the two first, (the third I need not notice) I would object 

 that there is no nation of antiquity, with whose every-day exist- 

 ence, their manners, customs and arts, we are so well acquainted 

 as with those of the ancient Egyptians; and that, whilst we 



