180 
DR. GLADSTONE ON CIRCUMSTANCES MODIFYING 
inonia, zinc, manganese, iron, lead, tin, cobalt, copper, nickel, bismuth, arsenic, mer- 
cury, antimony, silver, gold, platinum, alumina, sesquioxide of iron, water, phlogiston. 
The suitability of some of the methods employed for arriving at these results has 
never, as far as I know, been questioned ; for instance, that zinc has a stronger 
affinity for sulphuric acid than manganese, or iron, or lead has, because it will sepa- 
rate any one of these metals from its solution in the said acid. Other methods how- 
ever are more open to objection, such, for example, as that which led Bergman to 
place baryta at the head of the series, because it took sulphuric acid from every other 
base. To such deductions as this, drawn from precipitation, it may be objected, that 
the tendency of the two bodies to combine has arisen more or less from the insolubility 
of the compound. Berthollet adopted this view; and in his ' Recherches sur les 
Lois de I’Affinite,’ he endeavoured to prove que les affinites electives n’agissent pas 
comme des forces absolues par lesquelles une substance seroit deplacee par une autre 
dans une combinaison ; mais que, dans toutes les compositions et les decompositions 
qui sont dues a I’affinite elective, il se fait un partage de I’objet de la combinaison 
entre les substances dont faction est opposee, et que les proportions de ce partage 
sont determinees non seulement par fenergie de faffinite de ces substances, mais 
anssi par la quantity avec laquelle elles agissent, de sorte que la quantite pent sup- 
pleer a la force de faffinite pour produire un meme degre de saturation*.” 
These two conflicting views were much discussed at the time when they were pro- 
pounded ; the attention subsequently paid to the laws of stoichiometry has removed 
much of the difficulty in which the subject was then involved ; Gay-Lussac has 
pointed out the erroneous idea of cohesion that obscured the reasoning of Berthol- 
let; and yet the amount of truth contained in either of these opposite opinions 
remains still an open question. 
It is novv some years since I first began to reason, and occasionally to experiment 
upon this subject. Since that time Malaguti has published a paper bearing upon it, 
which will be referred to subsequently ; Bunsen and Debus have experimented, and 
independently arrived at a very remarkable law ; and Williamson has on more than 
one occasion vindicated the views of Berthollet. 
Bunsen 'I' exploded together carbonic oxide, hydrogen or cyanogen with oxygen, 
and, after varying his experiments greatly, deduced the following conclusions: — , 
1 . When two or more bodies B, B', are presented in excess to the body A, under the 
circumstances most favourable to their union, the body A takes from each of them 
B, B', . . . . quantities which always stand to one another in a, simple relation ; so that for 
1 , 2, 3, 4 atoms of the one compound, there are formed 1, 2, 3, 4 atoms of the 
* Bergman even had some perception of the influence of quantity, as when he says, — “ Jam ulterius restat 
explorandum, num omne d sufliciente c possit unione pristina extrudi. Probe hoc in genere notetur oportet, 
decomponentis c duplo, triple, immo interdum sextuple majore opus esse quantitate, quam quse rw A libero 
saturando suffleit.” He failed, however, to see any particular significancy in this fact. 
t Ann. Ch. Pharm. Ixxxv. 137. 
