190 ANNUAL OF SCIENTIFIC DISCOVERY. 



the number adopted by chemists for that metal resting on the author- 

 ity of a single experiment of Berzelius, the author considered it of 

 importance on practical as well as theoretical grounds to institute some 

 new experiments on the subject. The salt of platinum selected was 

 the double chloride of potassium and platinum ; which, after being 

 dried in vacuo, at a temperature of 1 05 Centigrade, was decomposed by 

 digestion with metallic zinc and a small quantity of water, the action 

 being assisted by the application of heat towards the end of the pro- 

 cess. After the complete precipitation of the platinum and the 

 formation of chloride of zinc from the decomposition of the double 

 salt, the excess of zinc was removed by the addition, first, of acetic, 

 and subsequently, of nitric acid. The precipitated platinum was then 

 removed by means of a small and carefully washed filter, and the 

 amount of chlorine in the solution of chloride of zinc ascertained by 

 Gay Lussac's process, which has been of late so successfully applied 

 by Pelouze to the determination of several other atomic weights. The 

 double chloride of potassium and platinum was found to retain 

 55-10, OOOths of its weight of moisture, even when dried at a temper- 

 ature considerably superior to the boiling point of water. In three 

 experiments performed by this process, the numbers obtained were 

 98.93, 98.84, and 99.06 ; the mean number 98.94 expresses, therefore, 

 the atomic weight of platinum. For the atomic weight of barium, the 

 author obtained from two closely accordant experiments the number 

 68.789 ; and concluded with some general observations as to the 

 importance of a systematic series of experiments to settle, if possible, 

 definitively whether the law of Prout, that the atomic weights of all 

 bodies are multiples of that of hydrogen, be universally true. He 

 concluded by reading an interesting extract from a letter which he 

 had received from Baron Liebig. " It is not certain that Front's law 

 may not be true for oxyen, nitrogen, and carbon, without its being 

 necessary to assume, as a consequence, that other bodies behave simi- 

 larly, that is, that their atomic weight must be exactly multiples by 

 whole numbers of the atomic weight of hydrogen. The law is cer- 

 tainly not true of all bodies, but it may be true of certain groups, 

 whose members, in respect to atomic weight, stand in a simple numer- 

 ical relation to each other. The atomic weights of silicium, cobalt, 

 strontium, tin, arsenic, and lead, are in the same ratio as the numbers, 

 1:2:3:4:5:7. We do not see the necessity of this relation, but only 

 the possibility. Why should fractional numbers only occur, and not 

 whole numbers also V I consider these relations only as facts : the law 

 of the numbers themselves is quite unknown to us, as unknown as 

 the absolute weights of the atoms." 



EARLY EGYPTIAN CHEMISTRY. 



THE following facts elicited by the recent unrollment of a mummy 

 at Bristol, England, were communicated to the Philosophical Maga- 

 zine, by Dr. Herapath. He says, " on three of the bandages were 

 hieroglyphical characters of a dark color, as well defined as if written 



