204 MEMOIR OF DR. DALTON, AND 



" D. When the numbers in the last series are compared with 

 those found by experiment, they are found to agree perfectly, 

 as far as regards alumina, lime, and magnesia. On the other 

 hand, the amount of baryta in the sulphate is 2224, but in 

 § XIX. 2226. No doubt the difference comes from the 

 greater difficulty in finding the point of saturation in the case 

 of this earth than in the case of the others, when combining 

 them with sulphuric acid. At the same time, the supposed 

 error is so small that it may be left out of consideration, for it 

 amounts only to -^i^^ or 0.0009 or to^o^o o, which is a diiference 

 that may be reckoned as nothing. It must be remembered 

 that decimal fractions only are used here. 



" E. Now if the quantities found by experiment exactly fit 

 into the series, if all the terms of these series entirely corre- 

 spond to the possibility of double affinity, if even a quantity 

 which is capable of neutrality, but not of double affinity, is 

 banished out of one series by the rule of the series ; further 

 if one series becomes possible only through the other, the 

 proposition is absolutely certain, that the quantities of the 

 hitherto known alkaline earths which enter into rest or 

 equilibrium with sulphuric and muriatic acids are terms of 

 an infinite series in arithmetical progression, each of which 

 proceeds according to its own law. 



' ' G. Shall we then conclude from the laws of the two series, in 

 which so many terms are wanting, that there are many alkaline 

 earths existing in nature ? So far as probability and possibility 

 are concerned it is a fair conclusion, especially since the know- 

 ledge of magnesia and baryta are the property of only the last 

 half century. If they had not been discovered until after the 

 study of the stoechiometric sphere had commenced, the second 

 and eleventh term of every series would be wanting, and a * 

 substituted, and besides it would not have been possible, with 

 such a small number of terms to have found out the law. 

 Who knows if there are not other elements in existence which 

 interrupt the last series as neutral quantities, precisely as with 



