1813.] Definite Proportions in Chemical Combinations. 297 



acid + 50"9 oxide. The mean of this gives us almost exactly 

 the numbers in the table. 



s This salt is given from analogy, never having been analysed. 



1 According to Proust, it is composed of 18 acid and 6S 

 oxide. Now 5 : 20 :: 18 : 72. This approaches pretty nearly 

 to the number found by Proust. 



u According to the analysis of Berzclius, this salt is composed 

 of 100 parts acid + 88 oxide of iron. Now 5 x 2 = 10 : 

 8-666 :: 100 : 86 660. This is within l£ per cent, of Berzes 

 ljus' analysis. 



x We are not acquainted with this salt. Supposing it to 

 exist, its composition must be as stated in the table. 



y The numbers in the table correspond nearly with the ana- 

 lysis of this salt by Berzelius. {Ann. de Chim. lxxviii. 223.1 

 According to him, it is composed of 100 acid + 266 oxide. 



Now 100 : 266 :: 5 x 2 : 266; and -y- = 8-866, a number 



nearly agreeing with the weight of deutoxide of iron. At the 

 same time I entertain some suspicions of the accuracy of Ber- 

 zclius' experiment 



■ I distinguish the salts containing peroxides by prefixing the 

 syllable per to the name. The persupersulphate of iron means 

 .-! salt composed of sulphuric acid and peroxide of iron with 

 excess of acid. The result in the table is derived from the ana- 

 lysis of Berzelius. He ibund it composed of 100 acid -f 655 

 peroxide. Now 100 : 65-5 :: 5 x 3 = 15 : 9-825. And 

 !>'825 differs very little from 9-666, the weight of an atom of 

 peroxide of iron 



' According to the analysis of Berzelius, sulphate of lead is 



l omposed of 100 acid + 260 yellow oxide of lead. {Ann. de 



I him. Ixxvii. B3.) Now 100: 280 :: 5 X 2 = 10 : 28. And 



thl weight of an integrant particle of yellow oxide of lead, 



ording to the table, is 27*974. 



I found ulphate of zinc to contain 25*8 acid + 28 2 oxide, 

 of an atom of acid) : 5\'il5 (the weight of 



