SODA. 



[ G9f) ] 



SPECTROSCOPE. 



Mefeorolocfie; Glaisher, Mic. J». 1Sj5, iii. ; 

 Nauiuanu, Alinerahu/ie. 



SODA. — KoUiker recommends a solution 

 of caustic soda, iu preference to potasli, for 

 the resolution of some of the tissues into 

 their conipt>ueut elements. We have been 

 unable to detect any marked dill'ereuce be- 

 tween the action of these two solutions; 

 and the former has the disadvantage of 

 lifting the stopper from the bottle by the 

 crystallization of the carbonate formed, so 

 that it is with diHicalty preserved. 



PI. 10. fig. 15 represents the crystals of 

 oxalate of soda ; and fig. 19 those of the 

 nitrate (Urea). 



SODIUM, Chloride of, or common 

 salt. — The crystals of this- salt belong to 

 the regiUar system. The most common 

 form is the cube terminated b}' quadrangu- 

 lar pyramids or quadrangular pyramidal 

 depressions, rectangular tables, &c. Schmidt 

 endeavours to show that the primaiy form 

 of the crystals is the octahedron, and that 

 the cubes are twin octahedra. The crystals 

 do not polarize light. (Schmidt, Entwurf 

 ein. allg. Untersuch. 90 ; and the Bibl. of 



CHE>nSTRY.) 



SCE.MMERIXG, Mirror of.— Intro- 

 duction, p. xxii. 



SOLENOPH'RYA, CI. & Each.— A 

 genus of Acinetina. 



Char. Sessile and with a membranous 

 lorica, tentacles simple, in distinct tufts. On 

 roots of Lemna. (Clap, et Each. Inf. 389.) 



SO'EIUM, Heib.— A genus of Biddul- 

 phieie (I)iatomacea3). (Rabenh. Ahj. i. ol9.) 



SOLORI'NA, Ach.— A genus of Phyl- 

 lodei (Eichenaceous Eichens). 4 species, in 

 mountainous districts. (Eeighton, Lich. 

 Fl. 106.) 



SORAS'TRUM, Kiitz.— A genus of Des- 

 midiacese. 



Char. Frond globular, composed of com- 

 pressed radiating cuneate cells, bifid at the 

 apex. 



S. spinosiim (PI. 3. fig. 22), in stagnant 

 turf-pools. 



Bibl. Kiitzing, Sp. Aly. 19.5; Rabenht. 

 Aly. iii. 81 ; Carter, Ann. N. H. 1869. 



SORITES, Ehr. See Amphisorus and 

 Orbitolites. 



SOROSPH^'RA, Br. — A free. Are- 

 naceous Foraminifer, with niunerous sub- 

 globidar thin-walled chambers (1-5" diam.), 

 loosely attached, and irregularly crowded. 

 H. confusa, in the Atlantic and Pacific, 

 900-2900 fathoms. (Brady, Qn. Mic. Jn. 

 n. s. xix. 9.) 



SOROS TOR A, Ilass.— A genus of Pal- 

 mellacete (Confervoid Algae) not clearly 

 distinguished from Glococapsa and Proto- 

 coccus. (Ilassall, A/r/cfl, 309.) 



SOROTHE'EIA, Kiirb.— A genus of Mi- 

 crolicJiens, parasitic on the thallus of /'///c- 

 iis art/ena. Spores 8, 2-locular, brown. 

 (Eindsay, Qn. M. J. 1869, 343.) 



SO'RUS. — The name applied to the ag- 

 gregation of sporanges of llie Ferns; some- 

 times applied also to the groups of spores in 

 the Florideous Alg;e. 



SPATHIDTUi^l, Du]. =Leucophn/s pt. 



SPATHUEA'RIA, P.— A genus of Dis- 

 comycetes (Ascomycetous Fungi), with a 

 fertile head running down the stem on either 

 side. S. Jiavida is one of our prettiest 

 Fungi when in perfection. 



Bibl. Grev. t. 165; Berk. Outl. t. 21. 

 fig. 7; Cooke, Handb. 661. 



SPECTROSCOPE, or Microspectro- 

 .SCOPE. — The spectrum-analysis uf coloured 

 microscopic objects may be effected by 

 means of one or more prisms in connexion 

 with the simple or compound microscope. 

 The prism, or combination of prisms, may 

 be placed, either beneath the achromatic 

 condenser, in the body of the microscope, or 

 in the eyepiece ; and this last arrangement 

 is usually adopted. Sorby and Browning 

 have perfected the microscopic eyepiece. 



Above the eye-glass of the eyepiece, 

 which is made achromatic and capable of 

 focal adjustment for rays of different refran- 

 gibility, is placed a tube containing five 

 prisms, two of flint glass interposed between 

 three of cro-wn glass in such manner that 

 the emergent rays which have been separa- 

 ted by the dispersive action of the flint-glass 

 prisms are parallel to the rays which enter 

 the combination. Below the eye-glass, in 

 the place of the ordinary stop, is a diaphragm 

 with a narrow slit, which limits the admis- 

 sion of light. Objects placed on the stage 

 of the microscope, provided they trar.smit a 

 sufficient quantity of light, may then be 

 examined, and their spectra observed. If it 

 is desired to corppare their spectra with any 

 other, provision is made for the formation of 

 a second spectrum, by the insertion of a 

 right-angled prism which covers one half of 

 the above-mentioned slit and reflects up- 

 wards the light transmitted through an 

 aperture in the side of the eyepiece. For 

 the production of the ordinary spectrum, 

 light is reflected into this aperture from a 

 smaU mirror carried at the side ; while for 

 the production of the spectrum of any sub- 



