Hunt. ] 174 [May 4, 
Thus hydrogen being 1 = H, the equivalent weight of carbon dinoxyd, 
whether as gas, liquid or solid is assumed as 44 = CO,; that of water in 
any of its states is taken as 17.96 = H,0, and that of the various forms of 
silica as 60 = SiO, ; while that of carbonate of lime, whether as calcite or 
aragonite, is 100 = CCaO,. These weights in the case of gaseous bodies 
are really the weights of equal volumes, compared with that of hydrogen 
at the same temperature and pressure, and are truly equivalent weights. 
The law of condensation, however, shows us that in the case of liquid and 
solid species we have to deal with much more complex formulas than 
these. In fact, the minimum equivalent weights deduced from analy- 
ses of the chlorids of the ammonio-cobalt bases give numbers of 500 and 
upwards, and in the case of a certain metaphosphate, equal 2,540. The 
complex potassio-cobaltic nitrite is represented by a formula giving an 
equivalent weight of not less than 958. These weights are surpassed by 
those deduced for the complex silicotungstates, and prosphotungstates, 
ourknowledge of which has been much extended by the late researches of 
Wolcott Gibbs on what he has called ‘‘the complex inorganic acids.”’ 
Therein he has made known the existence of progressive or homologous 
series, the successive terms of which differ by 2WO,, and rise from 
4WO, to 24WO,, and even 60WO,; having formulas from which the 
minimum molecular weights deduced are represented by many thousands, 
H=1. Thus the golden insoluble crystalline compound of tungsten, 
oxygen and sodium described by Wobler is probably, according to Gibbs, 
16WO,. 4WO,. 7Na,0 = 5,002., while to another crystalline species, sol- 
uble in water, and hydrous, he ascribes the formula, 
G0WO,, 3P,05. 2V,0; VO,. 18BaO + 144H,0 = 20,058, 
This, according to him, has ‘‘the highest molecular weight yet observed.” 
The studies of Gibbs and of many others, whose work in this field has 
been briefly summarized by the writer (Mineral Physiology, etc., pp. 
386-889), unite in showing that a great complexity of composition may 
exist in definite crystalline compounds, and moreover that very small 
portions of different substances may not only occur as necessary elements 
in such a compound, but may even change essentially its chemical rela- 
tions. Thus in a complex tungstate containing 12WO, = 2784, the addi- 
tion of SiO, = 60, suffices to determine the production of a new type, 
with changed basicity. In like manner the addition to a compound con- 
taining 24WO, = 5568, of P,O; = 142, gives a new and distinct acid type. 
Moreover, oxygen in these bodies may be in part replaced by fluorine ; 
while platinum, selenium, tellurium and many other elements may enter 
in small but definite amounts into the polytungstates and polymolybdates, 
as well as organic radicles, such as methyl, ethyl and phenyl. These 
remarkable results are regarded by Gibbs as forming ‘‘ a new department 
of inorganic chemistry.’’ In commenting upon them, however, it has 
been elsewhere said : 
“Tt will be remembered that I had already, in 1853, proclaimed that 
