ON FOCAL IMAGES. QQj 



du&ion of fo large a quantity of palladium as was offered for 

 fale, that a proportional quantity of platina, from which the 

 whole was extracted, was purchafed by me a few years fince, 

 with the defign of rendering it malleable for the different 

 purpofes to which it is adapted. That object has now been 

 attained, and during the folution of it, various unforeseen 

 appearances occurred, fome of which led me to the difcovery 

 of palladium ; but there were other circumftances which could 

 not be accoonted for by the exifience of that metal alone. 

 On this, and other accounts, I endeavoured to referve to 

 myfelf a deliberate examination of thoie difficulties which the 

 fubfequent difcovery of a fecond new metal, that I have 

 called rhodium, has fince enabled me to explain, without 

 being anticipated even by thofe foreign chemifts, whofe at- 

 tention has been particularly directed to this purfuit. 

 I remain, Sir, 

 Your obliged and obedient Servant, 



W. H. WOLLASTON. 

 Feb. 23, 1S05. 



X. 



Short Remark on Mr. Walker's lafi Letter refpefting Focal 

 Images. By C. L. 



To Mr. NICHOLSON. 

 SIR, 



1 WOULD beg your indulgence for a very fhort letter, in C. L. decline* 

 anfwer to Mr. Ezekiel Walker. The only reply which feems an * farthe / dlf ' 



J * J cuiiion refpsct- 



needful, on the fubjecl of the temper in which he or I may ing Mr. Walker's 

 have written, is that if his firft paper had indicated more f"P^ ri ™ entswith 

 the calm fpirit of philofophy, as well as of philofophical cor- denies 'the facts, 

 recfnels, my obfervations might either have been unneceffary, 

 or, perhaps, drawn up without any extianeous remark. As it 

 is, I do not think myfelf entitled, nor am I indeed inclined 

 to offer any ftriclures upon his laft ; which I leave to the un- 

 biased judgment of your readers. On the prefent occafion, 

 I only with to adhere to the experiments. Men of fcience 

 will find no difficulty in forming a proper eftimate of our 

 reafonings. In plain language, therefore, I will beg leave 



ta 



