1819.] Scientific Intelligence. 467 



intend to insert in an early number of the Annals of Philosophy. 

 At present I shall merely observe that Berzelius has adopted my 

 view of the subject, which his experiments seem to me to esta- 

 blish in a satisfactory manner. I have been a good deal gratified 

 to perceive that all the new determinations that have been made 

 since the publication of my last edition approach nearer than the 

 former ones to the numbers which I have pitched on for the 

 weight of the atoms of bodies. 



According to Berzelius's new analyses, these two acids are 

 composed as follows : 



Arsenious acid. . . 100 arsenic + 3 1*907 oxygen 

 Arsenic acid 100 + 53-179 



numbers which almost coincide with those which I have already 

 given, partly from my own experiments, and partly from those of 

 Proust. 



Berzelius found arseniate of lead composed of 



Arsenic acid .. 34-14 100-00 .... 7-257 



Oxide of lead.. 65-86 .... 192-91 .... 14-000 



I have added the last column in the preceding table, from 

 which we see that if 14 be the equivalent number for protoxide 

 of lead, as I have shown it to be, then the equivalent number for 

 arsenic acid is 7-257. Now 7-25 is the number which I assigned 

 for arsenic acid in my System ; therefore I consider the analysis 

 of Berzelius as corresponding exactly with my previous views. 



Berzelius formed two arsenites of lead. The first, by precipi- 

 tating nitrate of lead by arsenite of ammonia ; the second, by 

 mixing together arsenite of ammonia and subacetate of lead. 

 The first of these he found composed as follows : 



Arsenious acid . . . 47-356 100-00 12-593 



Protoxide of lead . . 52-644 .... 111-17 .... 14 000 



The composition of the second was as follows : 



Arsenious acid 100-0 6-377 



Protoxide of lead 219-5 14-000 



It is quite obvious that the first of these salts contained twice 

 as much arsenious acid as the second. If we consider the 

 second as composed of one atom acid and one atom base, then 

 the first must be a compound of two atoms acid and one atom 

 base. On this supposition, the equivalent number for arsenious 

 acid will be : 



By first salt ....". 6*296 



By second salt 6-377 



Mean 6-336 



The number which I had chosen is 6-25. Now I consider 



2 g 2 



