THE AMERICAN THE SPINDLE MINERALOGIST, VOL. 47, JULY-AUGUST,1962 STAGE: A MODIFICATION HYPODERMIC SYRINGE UTILIZING A M. J. OeraNranrrn,Department oJ Geology,Hebrew Uniaersity, Jerusolem, Israel. ABSTRACT A new spindle stage is described built around a hypodermic syringe. Advantages of the simple design include rigidity coupled with smoothness of rotation. INrnonucrrow The use of the spindle stage is now well establishedin mineralogical practice. The diverse designsdescribed,together with a generalaccount of their operation,have been summarizedby Wilcox (1959).A new form of stage is described hereunder which is simple in its construction yet robust, convenient to use, and capable of yielding results of acceptable accuracy. GBNBnar,DBscnrprroN A mounted stage is shown in Fig. 1. It consistsof three assemblies. There is firstly the hypodermic syringe to which the measuring pointer and protractor are attached with the aid of rubber tubes. Secondly,there is the glasscell, in which the immersion liquid is held; several cells'may be prepared for each stage. The cell is an independent unit which can be removed completelyfrom the stage;it has a channelsawn into one side for introduction of the needle-mounted grain. Thirdly, there is a wooden base plate on which the syringe is held, and to which the glass cell is clamped by the ordinary microscope clips; the base plate is screwed onto the rotating stageof the microscope. A dismantledstagecan be seenin Fig. 2. The syringe assemblyis held on the base-plate by the rivetted strip of plastic tubing; whereas the entire syringe can be moved forcibly-during initial assembly and for purposes of centering-it remains stable while the plunger is rotated. Apart from the addition of rubber tubing for holding the measuring devices, the only modifi.cation of the syringe which is necessaryis that the tip of the plunger be sawn off; a small amount of cork is stuffed into the hollow thereby exposed.The needle on which the mineral grain is to be mounted will be stuck, pointed end first, into this cork. The mineral may therefore be rotated by turning the plunger head while the syringe housing is clamped to its base. When mounted in this manner the grain will be about one centimeter above the height at which a rock-slice would normally lie on the microscope stage. For this reason it may not be possible to exploit the full numerical aperture of the high power objective for the examination of 904 M. J. OPPENHEIM Frc. 1. The mounted spindle stage. The microscope has been fitted with a universal stage objective (Zeiss UD 20) for conoscopic observations' interferencefigures unless some adaptation is made to the microscope substage.on some microscopesit is sufficient to remove the upper stopscrew from the condenserrack, thereby enabling elevation of the condenserlens. Alternatively an accessorylens may be insertedbetweenthe needleand condenser:the simplest such arrangementis replacementof the standard condenserby one designedfor conoscopicwork with the universal stage. Mrruoo oF UsE Before use, a few drops of glycerineare inserted within the syringe to act as a lubricant: the movement thereafter will be at once firm yet delicate. A broken-off needle is used for mounting the grain; any available needlewill serve,such as a domesticor hypodermic type, as long as it is thin enough to pass through the tip of the syringe. Irregularities left on the broken needletip should be ground ofi, for they will render cementing the grain difficult. Dental wax' as recommendedby Rawlins and Hawkstey itsg+) was the first glue tried by the author, and as it has proved SPINDLE STAGE 905 Frc. 2. I'he spindle stage dismantled. The plastic strip (3 mm thick) is rivetted to the plywood base plate (5 mm thick) The tube around the syringe housing is to clamp the protractor in place. l-rc.3.'I'he glass cell (without liquid or cover-slip) Constructed solely of microscope 'I'here siides glued by dental u,ax. are no optimal dimensions for the channel: a larger opening facilitates manipulation but requires more liquid. M. J. OPPENHL:IM satisfactory none of the other recipesto be found in the literature have been tried. The needleneedsbe but slightly warmed before touching it to the strip of wax; the blob of wax which forms immediately around the needle tip will remain sufficiently soft during several secondsfor the attachment of a grain. After the grain has been mounted on the needle the latter has to be attached to the plunger. With the plunger in position, the mounted needleis lifted with forcepsand the sharp end passedthrough the opening of the syringe and pressedfirmly into the cork which is within the piungershaft. Ensuring that the needle is emplaced firmly, the grain is centered, whiie observingit through the microscope,by manipulating the syringe bodily within its plastic clamp (Fig. 1); this is a simple and rapid procedure. The plastic tube will retain the synnge rn rts new posltron. Having mounted and centeredthe grain, a ceil is filled with the selected liquid and coveredwith a cover slip. The cell is then placed on the stage and brought up carefully until the grain is enveloped.Once in pla,ce,the cell is clampedwith one or both of the stageclips. Optical observationsof the grain may now be begun. Liquids are changedafter removing the celi and brushing it in a small bath of acetone.The celi is chargedrvith the new liquid, a cover slip put on, and returned to the stageas before. Aovar.tracps oF THE Dosrcx Nlechanicalperformanceof the stageis good. Nlovement of the spindle is free yet amenableto precisecontrol, and the grain may be rotated a full 360 degrees.The removability of the glasscell facilitatesits washing,aithough further cells may be held ready for immediate interchangewithout pausingto wash the first one.As severalneedlesmay be kept to hand, a seriesof pre-mounted grains may be speedi}y examined. X'Ieasured grains may be stored in their original orientation, or perhapstransferred to a mounting on an r-ray machine. AcrNowreocMENT The author wishes to thank his dentist, Dr. n,I. Wiener, for kindly providing the wax. RrlrnnNcns Rawr.rxs, F. I. G. aNo C. W. Hnwxsr.nv (1934), A cell for refractivity measurements on minute cr)'stals . f our. Sc'i. Instruments,Il, 282-28+ Wrrcox, Rav E. (1959), Use of spindle stage for cletermining refractive indices of crystal fragments Am. Mineral., M, 1272-1293. Manuscript receiaeil,November 25 , 1961.
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