38 | SCIENCE. 
posits, known as the ‘‘solid soda,” consists of a mass of 
crystals mixed with a considerable amount of black 
slime. Analysis shows: Na. SO,, 36 per cent; CaSO, , 
1.45 per cent; Mg Cl. , 0.77 per cent; Na Cl, 0.21 per 
cent; H. O, 46.87 percent; insoluble residue, 13.86 per 
cent. The upper part of the deposit from 3-12 inches 
thick is formed by solution from the upper layers of the 
lower part, and by subsequent evaporation or cooling 
of the solution. Calculated as anhydrous, the composi- 
tion of this upper portion is: Na. SO,, 99.73 per cent; 
Mg Cl, , 0.26 per cent; insoluble matter, trace. The 
article, however, as prepared at Laramie is said to be 
not so pure. 
ARTIFICIAL PYROXENES, ETC. 
A contTrisuTion to the artificial production of min- 
erals in a general method for the production of anhy- 
drous crystallized silicates is described by Dr. Hermann 
Traube. The amorphous hydrated silicate is precipi- 
tated from a solution of the salt of the metal by the ad- 
dition of a solution of sodium silicate. The precipitate 
is heated to a high temperature for several hours with 
boric acid, and the anhydrous silicate is finally obtained 
in good crystals. Ebelmen has already prepared the 
mineral pyroxene by this method, but Dr. Traube ex- 
tends its application toany of the corresponding metallic 
salts. For instance, beautiful crystals of zinc bi-silicate, 
Zn Si O;, are obtained by precipitating the hydrous 
silicate from asolution of Zn SO, by addition of sodium 
silicate. The precipitate isignited with eight times its 
weight of fused boric acid and finally the boric acid not 
volatilized is leached out with water. The crystals of 
Zn SiO; occuras transparent prisms with domal termina- 
tions. By the same method the mixed silicates of this 
class may be obtained. 
STEREOCHEMISTRY AND MOTOCHEMISTRY. 
In view of the recent extended study awarded this com- 
paratively new fieldin chemistry, historical notes of its 
earlier conception become of interest. In addition to 
the hints regarding geometrical arrangement in space 
offered by Swedenborg, Wenzel, Biot, and some others, 
we have the same ideas foreshadowed in the writings of 
Wollaston and Ampere—quoted by Prof. John C. Cain, 
of Owens College, Manchester, in a recent letter to 
Nature. Wollaston in his paper entitled, ‘‘On Super-acid 
and Sub-acid Salts” (Phil. Trans., Vol. XCVIII, 1808) 
discusses the constitution of the two oxalates of potash: 
‘When our views are sufficiently extended to enable us 
to reason with precision concerning the proportions of 
elementary atoms, we shall find the arithmetical rela- 
tion alone will not be sufficient to explain their mutual 
action, and that we shall be obliged to acquire a geom- 
etrical conception of their relative arrangement in all 
the three dimensions of solid extension... When the 
number of one set of particles (combined with one par- 
ticle) exceeds in the proportion of four to one, then, on 
the contrary, a stable equilibrium may again take place 
if the four particles are situated at the angles of the four 
equilateral triangles composing a regular tetrahedron... 
It is perhaps too much to hope that the geometrical ar- 
rangement of primary particles will ever be perfectly 
known.” 
The same idea was developed later by Ampére in his 
‘Letter to Berthollet” (1814), in which he considers the 
molecules as forming various geometrical figures de- 
pendent on the number of atoms contained therein. 
Under the designation ‘‘Motochemistry’’ M. E. Mol- 
inari has recently discussed the hypothesis that the con- 
stitution of compounds is dependent on the intromolecu- 
lar movements of the atoms in relation to one another, 
- [Wol. XXIII. No. 572 
rather than on their relative positions in space. The 
bonds by which it is customary to represent the union 
of atoms are taken as expressing the nature of the swing 
or energy of the atoms with regard to each other. 
CONTINENTAL PHENOMENA ILLUSTRATED 
BY RIPPLE MARKS. 
BY RICHARD E. DODGE, CAMBRIDGE, MASS. 
A rew days ago I saw at Winthrop Beach, Mass., 
some peculiar features of ripple marks that I thought 
might be of interest to the readers of Science. 
Walking along the beach close to low-water mark, I 
noticed from a considerable distance a large number of 
peculiar markings upon the surface of the ripple marks, 
with which the shore was extensively corrugated. The 
sand of which the ripple marks were composed was 
very micaceous and much mixed with fine mud, so that 
it held a large amount of water between the particles. 
There was also a thin film of water on the surface of 
the deposits, partially held in position, I suppose, by 
cohesion. The ripple marks had an amplitude of about 
eighteen inches, and in the hollows between two adja- 
cent marks the film of water was somewhat thicker 
than on the sides, so that a shallow basin was thus 
formed, bearing the same relation to the sloping sides 
of the ripple marks that the ocean itself bears to the 
adjacent continents. 
After having noted the conditions mentioned above, 
I saw that the peculiar markings were due to the ero- 
sion caused by the water running down the sides of the 
ripple marks toward the hollows. The seaward sides of 
the marks were being worn away and dissected by a small 
river system developed thereon, and the waste thus de- 
rived was being deposited in the adjacent hollows. We 
have thus in these ripple marks, left uncovered by the 
receding tide, constructional forms similar to what we 
might expect to see when a warped coastal plain 
emerges from beneath the ocean. 
As we would normally expect on such a construc- 
tional surface, we had developed at once a drainage 
consequent on the slope and structure of the materials 
of which the slope was composed. The streams, small 
as they were, followed all the laws of the largest conti- 
nental streams, at once deepening mouthwards and 
lengthening headwards toward the divide formed by 
the crest of the ripple marks. Such small river systems 
were developed at frequent intervals along the slope of 
the ripple mark, each one having numerous tributaries 
and assuming a digitate form so familiar in rivers. 
As soon as the small stream reached the level of the 
half-inch film of water in the basin between the ripple 
marks, erosion ceased and deposition began. In front 
of each small stream there was building out into the 
basin a small delta, but very broad and as deep as was: 
the layer of water. The discharge of the minute frag- 
ments of waste from the streams was so rapid that I 
could watch the growth of the delta with ease and could 
note the building forward of the frontal slope and the 
building up of the top slope to the surface of the water, 
as has been described by Prof. W. M. Davis in his des- 
cription of the growth of glacial sand plains. We thus 
had forming a small continental shelf similar to that off 
the eastern coast of the United. States at the present 
time. 
A more careful study of the processes in operation in 
these basins showed me that at certain places the small 
streams were developing alluvial terraces and at others 
building alluvial plains according to whether the stream 
was over or under-loaded with waste to be carried down 
