Fig, 10. Illanus ambigutis, n. sp.; a, lateral view of a head, the associated
movable cheek figured ; b, posterior view of the glabella ; c, view of the same
F^. II. IlUentis ambiguus^ n. sp.; movable cheek ol unusually large propor-
Fig. 12. Grammysia Casweliiy n. sp.; a, lateral view of the shell, anterior
definition too sharp ; b, view of the same from above.
Fig. 13. tripUsianus^ n. sp.; a, view of one of the valves; b, lat-
eral view of the same shell. ^
Fig. 14. triplesianus, n. sp.; view of the other valve from a different
Fig. 15. Strophostylus cyclostamusy Hall; lateral view of a specimen.
Fig. 16. Trochonema nana, n. sp.; two views, magnified to eight-thirds and
four-thirds of the original size respectively.
Fig. 17. Cyclora alta, n. sp.; a, lateral views of specimens showing variations
in the elevation of the spire ; b, view of the umbilicus of a specimen ; all views
magnified two diameters.
Fig. 18. .Raphistoma affinis^ n. sp ; view from above, and also a lateral view,
the umbilicus being directed upwards.
A COMPEND OF LABORATORY MANIPULATION.
It is the design of the series of papers, of which this is the first, to
present in concise form the methods of investigation which have proven
themselves of greatest service in the laboratories of this country and
Europe. No attempt at originality or completeness is made, but only
such methods as have been experimentally proven useful will be admit-
ted, while free use will be made of the modern text-books of Fol and
It is acknowledged by all students that the proper method of re-
search is the first essential to the prosecution of any line of investiga-
tion, and it is often stated that he who spends but half the time allotted
to a given study in experimentally learning the best manipulation to
employ, need not regret the time so spent.
The present paper deals with lithological appliances and methods
and is supplemented by a condensed translation and adaptation of Hus-
sak's * * Einleitung. " No apology is necessary for reducing the for-
mulae to the system in vogue in this country nor for giving prominence
to the subject of lithology, in view of its rising importance and increas-
A. Rock Sections.
In no department of geology has there been so great an advance
of late in this country as in the study of the intimate structure of rocks
by means of thin sections. The science of lithology is rapidly
evolving from a chaotic condition and assuming the similitude of a sys-
tem. Although the pursuit of this study has been confined to a limit-
ed circle and it has scarcely appeared in our literature, much may b^
expected in the near luture.
122 BULLETIN OF THE LABORATORIES
The impetus given years ago by Zirkle, in his * * Microscopic Pe-
trography," has slowly become apparent. Hawes, in his work upon
New Hampshire lithology, contributed substantial material to the same
science, while the more recent reports of the Wisconsin geological
survey affdrd evidence that the work is going on. Several of the
State geological surveys are now in the midst of investigations in this
direction the results of which may be looked for with great interest.
The United States surveys are not behind in cultivating the promising
Great as is the promise of research in this direction, we are equally
interested to observe that the introduction of the new method of study
of rocks is to a degree revolutionizing the study of geology. The
same methods which have so greatly augmented the disciplinary value
of biology by connecting histological and laboratory practice with its
study, are introduced into the courses in geology and the student is
taught to see through, as well as to look at, rocks and minerals.
The study of a rock or mineral involves, first, the investigation of
the origin, age, and relations of the rock, which invoke respectively
the sciences- of geotechnical, historical, and stratigraphical geology ;
second, the study of the rock itself, which may be carried on by means
of chemical and physical tests. Under the latter head come crystal-
lography and physical mineralogy. The chemical examination in-
volves the application of heat, as in blow-pipe analysis, or of chemical
reagents in the wet way.
The physical examination of minerals may be conducted micro-
scopically or macroscopically, depending upon the employment or non-
employment of aids to ordinary vision. Ordinary physical mineralo-
gy is occupied with such of the optical or other characters of minerals
as can be made out with the unassisted eye.
In order to prepare a mineral or rock for microscopic examination
it must, in most cases, be reduced to a transparent condition in order
that it may be studied by transmitted light. The facts which can be
obtained by the microscopic examination of opaque masses in reflected
light, are few and unimportant.
A rock may be reduced to a powder and mounted in a transparent
medium and many of its elements detected by microscopic examina-
tion of the angles and surfaces of the fragments. In this way parti-
cles too small for measurement by the ordinary goniometer may be de-
termined. Such of the resulting particles as are transparent may
OF DENISON UNIVERSITY. 1 23
be optically examined, though there are many opportunities for error.
It is recommended that rocks of a rather finely granular structure be
examined in this way with reference also to the specific gravity. A
fragment of suitable size is reduced to a powder, the fineness of which
may vary with the size of the granular elements in the sample. The
powder is then assorted under water by agitating repeatedly in a bottle
and hastily pouring off the fluid, leaving the part first to settle and re-
peating the process as often as any separation is possible. Denser
fluids (See Hussak Anleitung, p. 51,) may be used with advan-
tage in some cases. By mounting different parts of the powder
thus sorted separately or under separate covers upon a single glass
slip, interesting qualitative and even approximate quantitative results
may be obtained.
Comparatively few minerals or aggregates are sufficiently transpa-
rent to permit of optical examination by transmitted light. A few of
these, as mica, gypsum, calcite, dolomite, etc., are adapted for study
without other preparation in any way. In cases where the cleavage
is irregular and does not permit the breaking out of tabular plates it
becomes necessary to mount the irregular fragments in a highly refrac-
tive medium, such as balsam, between glass slips, and thus to ehmi-
nate as far as possible the dispersion and irregular refraction. Even
then the results are often unsatisfactory. Sands and other fragment-
ary rocks may be examined by the following method, suggested by
The powder or sand is mixed with about ten times its volume of
zinc oxide, then silicate of potassium is stirred in till the whole assumes
the consistency of a stiff" broth. This, while still soft, may be pressed
into a mold, formed from a section of a glass tube glued to a slip.
When set, the resulting cylinder is removed and fastened to a slip of
thick glass and ground in the way described beyond for compact
When a rock or mineral is not transparent and does not admit of
breaking into sections of suitable thinness with the hammer, it becomes
necessary to cut or grind a section of sufficient transparency and then
mount it between glass in Canada balsam. Before beginning this
somewhat tedious process the student should provide himself with the
following outfit : ( i ) A number of thick squares of plate glass about
one half inch thick and two inches square, these being ground on the
edges in order to avoid cutting the fingers ; (2) several dozen slips of
124 BULLETIN OF THE LABORATORIES
thin perfect glass for mounting the sections, the size preferred being
45 by 25 mm. and is furnished by any dealer in microscopes; (3) a
corresponding number of covers of thin glass, square in shape and
large enough to extend nearly across the slip; (4) ajar of balsam nearly
solid or of the consistency of honey and lumps of solid balsam, (the
balsam thould be in a wide-mouthed botrie covered with a protecting
shield or glass stopper, through which extends a dipping rod); (5) sev-
eral grades of emery powder, it being convenient to have numbers o,
and I, and emery flour, as well as a small quantity of emery slime.
This last is not kept by ordinary dealers and is made by decanting off
the finest impalpable powder during the grinding of other grades. It
may be secured of Julien, of New York, or through Bausch & Lomb,
of Rochester; (6) an alcohol or gas lamp; (7) a heating table or tri-
pod with brass plate, for heating the slides ; (8) a number of spring
clothes pins, with the lips filed flat, to hold the cover glasses while the
balsam drys; (9) a bottle of solution for cleansing the glasses, which
is prepared from sulphuric acid and chrbmate of potash ; ( 10) a contri-
vance of some sort for grinding or sectioning the rock. The simplest
way is, after breaking as thin a fragment as possible from an un weathered
sample, to grind one side of the fragment upon a smooth iron surface with
coarse emery and water until a plane surface is secured as large as a quar-
ter or larger. The surface is then ground with emery flour upon a large,
smooth plate of glass, after which a polish is secured by long rubbing
on a second plate with emery slime. The surface thus prepared is
glued to one of the squares of plate glass with balsam. The best
results are secured by using balsam which is quite hard but not yet
brittle ; it should yield to the nail with difficulty, but should not shiver
into fragments. A small piece is placed on the cleaned surface of the
square and set on the brass plate of the tripod over the flame of the
lamp. The chip of rock is also heated at the same time. When
the balsam has become thoroughly fluid, but before bubbles appear,
the section is pressed firmly down upon the balsam and as much of it
pressed out as possible. Care should be taken that no bubbles or im-
purities find their way between the section and the glass. A weight
or spring may, in some cases be necessary to prevent the slightest ele-
vation of one side of the chip from the glass square. The balsam
will set very quickly and, if the heating has been slow enough, will
have become tough â€” it should no longer yield to the nail. The older
lithologists advise the use of soft balsam, which is heated until it ac-
or DENISON UNIVERSITY. 1 25
quires the proper consistency before each mounting, in a spoon, but
there are many objections besides the tedious process involved. When
any number of slides are to be made there is economy in having bal-
sam of the proper sort at hand and if some becomes brittle it may be
melted with some which is yet too fluid. It is desirable also to per-
form the same part of the process with a number â€” say a dozen â€” sam-
ples at once, as it saves time and the chances of accident are fewer,
provided care be taken to avoid loosing the identity of the specimens.
After the chip has been glued to the glass square the former is ground
carefully with coarse emory of various grades until the section shows
signs of falling to pieces, it is then put upon the flour and slime plates
in succession. Great care must be used to prevent the accidental
mixture of coarse emery or gritty grains with the emery flour or slime,
as one grain of coarse grit may suffice to destroy the section just when
completed. When the section is judged thin enough, it is proved
by cleaning the square and laying it over print which should be clearly
seen through the section. The superfluous and soiled balsam is care-
fully cleaned away from the section and it is placed on the heating
table on which are also laid the slip and cover glasses. When the bal-
sam is fluid, a small fragment of somewhat more fluid balsam than that
previously used is placed on the glass slip and the thin section is
pushed off" the plate glass square with a blunt needle, the cool needle
adheres to the section and the latter is removed to the now perfectly
fluid balsam on the glass slip. The warm cover glass is now quickly
placed over the section which has been completely immersed in the
medium. Care must be taken that a sufficient quantity of balsam is
used to completely fill the space between the slip and the cover and
also that no bubbles arise to obscure the field. . If all has been suc-
cessful the spring clips are applied and the slide is placed aside to dry
without attempting to clean away the superfluous balsam. In a day
or two this will be hard enough to be readily removed with a knife and
the slide may be cleaned with a soft cloth wetted with alcohol, care
being taken that the balsam under the cover is not attacked by the al-
cohol. The slide is then ready to label in any convenient way, the
number of the corresponding hand sample being in every case attached
to the slide.
The process above described is less tedious than might be supposed
but can be materially shortened by the use of a lithological lathe pro-
vided with lead and iron horizontal laps. The accompanying wood
126 BULLETIN OF THE LABORATORIES
cut illustrates the form of lathe used for this purpose in our own labo-
ratory. It was manufactured at the suggestion of this department
and is not only more convenient and elegant, but less expensive than
any -other iathe at present in the market. It is constructed by W. F.
and John Barnes Co. , of Rockford, 111.
In the study of the section thus prepared a microscope is used
which is especially arranged for this purpose. The appearance of
such an instrument is illustrated by the accompanying figure which
OP DENISON UNIVERSITY. V%fJi
represents the polarizing microscope prepared by Bausch and Lomb,
Rochester, N. Y., while figure i. of plate XI gives a diagram of the
optical parts, etc. , of the Fuess-Rosenbusch stand in use in Germany.
The rotating stage is centered and graduated to record the angular
position of the slide. The polarizer (rr) is placed below the stage
and consists of a Nicols' prism set in a rotating cylinder. Above, it, is.
128 BULLETIN OF THE LABORATORIES
a condensing lense for making the rays convergent. The light is
polarized in one plane by the polarizer and (the condenser being re-
moved) passes through the section placed over the aperture in the stage.
The resulting image is now magnified by the microscope in the usual
way. Above the ocular is placed the analyser, consisting of a
Nicol's prism set in a revolving cylinder with a graduated limb. This
prism serves to cut off all the rays polarized in one plane by the lower
Nicol when its axis is at right angles to that prism. If, however, the
interposed mineral section is double refractive and rotates the plane of
polarization of the light, this fact is indicated by the fact that the field
does not appear dark when the Nicols are at right angles, but at some
other angle which enables us to ascertain the amount of rotation pro-
duced by the mineral in question. A quartz plate (zz) is inserted
above the objective and serves to discover the slightest double refrac-
tion. An artificial calcite twin, known as the Calderon plate, is in-
serted, in one of the oculars. If the mineral examined be not isotro-
pous the two parts will be unequally dark, thus enabling us to distin-
guish the optical characters by a most sensitive test. A plate of cal-
cite, set in a cork ring, is also used between the ocular and analyzer.
The interference figure produced by the calcite now is superposed upon
the mineral section and may or may not be distorted by the action of
the latter, affording another criterion by which to determine the min-
B. Micro-chemical Methods.
In the application of chemistry beneath the microscope,. tests of
prime importance are derived from the solubility of the various parts
of a section and the forms of crystals formed from an evaporated pre-
cipitate after a reaction is accomplished.
In order that the tests may be applied to but a single crystal of a
section, it is necessary to perforate the cover glass with a minute open-
ing, thus preventing the uncertainty otherwise unavoidable. An or-
dinary cover glass is coated with wax and a minute perforation is made
with a needle, exposing the glass, which is then subjected to the action
of hydrofluoric acid until the glass is eaten through by a perforation
less than a millimeter in diameter. The section is then covered and
the opening is brought directly above the crystal to be studied. The
balsam is removed by alcohol and the surface of the crystal is thus ex-
posed to the action. In the case of reagents giving off corrosive.
OF DBKISOK UNIVERSITY. lag
fumes, the objective may be protected by a thin glass cover tempora-
rily fastened to the end by glycerine.
As an example of the micro-chemical process we may mention the
process of distinguishing apatite from nephelin. If the grain of
apatite can be isolated it is dissolved in a concentric nitric acid solution
of molybdate of ammonia. As the solution is slowly affected, a
multitude of yellow octahedrons of lo Mo O3 + PO4 (NH 4) s appear
about the edges. This detects the phosphoric acid. The lime may
be demonstrated by dissolving the grain in nitric acid, to which is then
added a drop of sulphuric acid producing small crystals of gypsum.
In case the questionable grain is in a section the acids may be
applied with a glass rod and then removed by a pipette to a glass slip
and there evaporated.
Nephelin fails to produce the reactions described but its solution
in concentric hydrochloric acid affords, on evaporation, minute cubes
of common salt which are very readily recognized.
Boricky has applied Fluo-silicic acid in the micro-chemical analysis of
many minerals. The reagent must be chemically pure and about
13 per cent, strong. It cannot, of course, be preserved in glass
vessels. Its availability arises from the fact that nearly all rock-
forming minerals are attacked by it and the resulting compounds afford
A slide is covered with a thin protecting layer of balsam and upon
this the particles to be examined are placed. When the substance is
very slowly affected the best results are obtained by applying the
reagent to the section itself If the mineral is easily dissolved the
various components appear approximately in their relative proportion
in crystals of various form. In cases where the mineral is but slightly
attacked, some of its components may first separate and thus make
necessary a repetition of the process, or it may be faciliated by first
dissolving these soluble substances in fluoric acid. The fiuo-silicates
crystallize most perfectly when 'evaporated and the watery solution
permitted to again evaporate on a second slide.
1. Fltw-silicate of postassium crystallizes in the isometric system,
usually in i-i in skeleton groups, also in i, and I. The reaction is
masked by presence of sodium, when apparently rhombic crystals i-n . m-i
2. Flt^-sificates of sodium give short hexagonal columns with 0>
130 BULLETIN OF THE LABORATORIES
I, and i-2. Incomplete crystals are barrel-shaped, presence of cal-
cium increases the size.
3. Fluo-sUicate of calcium occurs in peculiar, long lanceolate
crystals, often in rosettes. The angles and edges are not sharp.
Monoclinic, easily soluble in water.
4. Fluo-silicate of magnesium appears in rhombohedrons the angles
of which are truncated by oR, and in combinations of R . i-2 or
R. i-2 . oR. It often appears in rhombohedrons deformed in one angle
or in cruciate or pectinate forms.
Ferric and maganesic compounds can hardly be distinguished from
magnesium fluo-silicate, and strontium compounds resemble fluo-
silicate of calcium.
5. Lithia compounds a^ear in obtuse hexagonal pyramids, while
fluo-silicate of barium occurs in excessively minute needles.
The fluorides of iron, magnesium, and maganese may be dis-
tinguished by subjecting them to the action of chlorine gas, which
changes the color of the iron compound to citron yellow, of the
manganese to reddish, while the fluoride of magnesia remains colorless.
Behrens gives the following method which, when carefully followed,
is exceedingly delicate : â€”
The sample to be studied is isolated and pulverized and is placed in
a covered platinum capsule not more than i cm. in diameter into which
a few drops of fluoric acid, fluoride of ammonium, and concentrated
hydrochloric acid have been placed, evaporate, and, if necessary,
repeat the operation. The dried mass resulting is evaporated with
sulphuric acid nearly to dryness, when gray fumes are formed. Add
water and again evaporate so that for each milligram of the powder a
centigram of fluid is produced. A drop of this fluid is now placed
on the slide with a capillary pipette and, after protecting the objective,
is examined for calcium. If calcium is presant, evaporation produces
crystals of gypsum (I . i-i' . i .) On the margin of the drop charac-
teristic swallow-tail twins may be found. . 0005 mg. of lime can be
detected in this way.
A drop of platinum chloride is now added and, if potassium was
present, strongly refractive octahedrons or trillings or quadrillings
Sodium is detected by cerium sulphate, a saturated solution of which
is placed on the slide near the drop to be examined and connected
with it by a capillary glass thread, In the drop of the reagent there
OF DENISON UNIVERSITY. I3I
appear desmid-like aggregates of cerium sulphate and on the margin a
brown cloudy zone of double salt of soda. Excess of sulphuric acid
prevents the reaction.
Magnesium is detected by salt of phosphorus. The drop, before
tested for possium or aluminum, is neutralized with ammonia and in a
drop of water placed at a distance of about i cm. is placed a grain of
salt of phosphorus and the two drops connected as before. The re-
sult is the production of double, forked crystalloids similar to those
found in natural glasses or well developed hemimorphic twins of
ammoniated magnesium phosphate.
Aluminum is detected by touching the drop with a platinum wire
dipped in caesium chloride. Translucent octahedrons of caesium
alumn are formed, or more rarely i . M. If the solution of the
mineral is concentrated, dendritic forms simply are formed and water
must be added.
Similar tests are proposed for the detection of other elements but
the above are of most general application.
C. Use of the Polarizing Microscope.
Ordinary polarized light is produced by placing the analyzer above the eye-
piece in such a position that its Nicol's prism stands at right angles to that in the
polarizer below the stage. The field now appears totally dark, inasmuch as the
only rays permitted to pass through the polarizer are extinguished by the analyzer.
All minerals are either simply or doubly refractive, and the former may be rec-
ognized as amorphous (like glass) or belonging to the isometric crystal system. In-
as much as the elasticity of the ether in either case will be the same in apy direction
in such minerals, they do not interfere with the rays which pass through them, hence
between crossed Nichols any section of such minerals remains constantly dark,
even though the section be passed through a complete revolution by rotating the
stage â€” in other words, the mineral is isotropous. Double refractive minerals, in
sections taken in some directions, become colored in certain positions between
crossed Nicols. Such sections become perfectly dark twice in one complete rev-
olution. These colors are due to interference of the rays brought about by the
OpticcU uniaxial crystals are those falling in either the tetragonal or hexagonal
systems. In such crystals there is but one direction in which there is no double
refraction, i. e. that parallel to the vertical axis ^, which, in this case, corresponds
to the optical axis. The elasticity of the ether contained in the crystal is differ-
ent in directions parallel and at right angles to the main axis. a= the axis of the
greatest elacticity and c= the axis of least elasticity. w= exponent of refraction