CHEMISTRY. 



105 



crystals, and the superfluous liquid removed by 

 applying blotting-paper to the edges of the 

 side. For hippuric acid, the solution, when 

 on the point of crystallizing, should be poured 

 on a cold slide, and, when the crystals have 

 formed, the remaining liquid should be poured 

 off, and the slide allowed to dry. Sugar, citric 

 and tartaric acids, and all substances very sol- 

 uble in water, may be obtained in crystals 

 by making a concentrated solution, filtering 

 it, and then pouring it on a slide, taking care 

 that only a thin layer of liquid remains, 

 which should be allowed to dry in the air. 

 To obtain crystals from sulphate of iodo- 

 quinine or 'Herapathite,' the author mixes 

 three drachms of spirits of wine, and one 

 drachm of acetic acid, in which he dissolves 

 ten grains of bisulphate of quinine. He then 

 pours ten or fifteen drops on a slide, and 

 adds a drop of tincture of iodine. When clear 

 he pours it from slide to slide as long as the 

 liquid holds out. The best method of obtaining 

 uric acid in crystals is, to allow eight or ten 

 ounces of urine to stand some hours, after the 

 addition of two or three drachms of acetic acid. 

 In a day or two the crystals will have grown 

 larger, when the bottle should be shaken, to 

 detach them from the sides ; then wash them 

 with distilled water, acidulated with acetic 

 acid. To obtain the rarer forms, it is requi- 

 site to allow the crystals to deposit quickly, 

 which may be done by making a solution of 

 urate of sodium, by boiling uric acid with so- 

 lution of caustic soda, until no more is taken 

 up. If one or two drachms of this are put into 

 eight ounces of urine, and a small quantity of 

 acetic acid added, not more than sufficient to 

 neutralize the soda, very perfect crystals will 

 be obtained. Another deposit found in urine is 

 the phosphate of ammonium and magnesium, 

 or triple-phosphate, which may be prepared in 

 prisms by dropping about twenty-five or thirty 

 grains of carbonate of ammonium into eight or 

 ten ounces of urine, and allowing it to remain 

 quiet for some hours. When the crystals are 

 of sufficient size, the bottle may be gently 

 shaken and the urine poured off. This deposit 

 may also be obtained in stellate crystals by 

 adding a drachm and a half to two drachms 

 of carbonate of ammonium to urine, and allow- 

 ing it to stand. The crystals should be washed 

 with distilled water, to which a little liquor 

 ammonias has been added. Calcic oxalate may 

 be obtained by dropping a single small crystal of 

 oxalate acid into eight or ten ounces of urine, 

 and leaving it at perfect rest for some hours. 

 Mr. Waddington has also obtained good results 

 from salicin, by pouring a saturated solution 

 in cold water on a slide, holding it over a 

 flame until it is at the boiling-point; then pour- 

 ing off the slide, when only a viscid film will 

 remain. This must become quite cold, and 

 the under surface held close to the flame of a 

 lamp or gas-jet. The moment it begins to 

 crystallize it must be removed a few inches 

 from the flame, or else it will fuse." 



Crystallization under the Blowpipe. It some- 

 times happens in experiments with the blow- 

 pipe, when borax, phosphorus, common salt, or 

 soda, is used, that the bead, at first limpid, be- 

 comes suddenly opaque. M. G-. Rose finds that 

 this is due to the development of crystallized 

 bodies in the interior of the mass. The crystal- 

 lization is often confused, although sometimes 

 it is very regular, and, on operating with tita- 

 nium under sufficiently varying circumstances, 

 M. Rose has been able to obtain anatase, and 

 to effect a crystallization of the two allotro- 

 pic states of the titanic acid. With felspar 

 and phosphorus salt (by the aid of which, as is 

 well known, silicates are reduced to silica and 

 phosphates), he obtained crystallized quartz, 

 confused, but insoluble in alkalies. In order 

 to recognize the crystals, obtained under these 

 conditions, flatten the yet warm bead and ob- 

 serve it under a microscope ; or it may be at- 

 tacked by water or an acid, in which case the 

 residual crystals may be collected on a glass 

 plate. (Chemical News, vol. xvi., No. 421.) 



Crystallization of Sulphur. M. Schutzen- 

 berger, of Paris, has made an interesting ex- 

 periment upon the crystallization of sulphur. 

 He filled a matrass, of a capacity of one hun- 

 dred and fifty or two hundred grammes, with 

 refined sulphur, commercially pure, so that, 

 when fused, the liquid occupied the whole of 

 the space below the neck ; the upper part of 

 the neck was drawn out into a capillary tube, 

 which was twisted several times, but left freely 

 open to the atmosphere. The sulphur being 

 melted in a bath of oil heated to 120, the flask 

 was placed in water heated to 95. In these 

 conditions, the sulphur remains perfectly fluid 

 for hours, even when occasionally moved and 

 drawn out of the hot water. If the tempera- 

 ture be made to fall very slowly, transparent 

 crystals, possessing the same density as the 

 melted sulphur, form either on the surface. or 

 in the midst of the fluid at about 90. The 

 mass of crystals gradually augments, but with 

 great slowness ; sometimes they are isolated, 

 sometimes united in groups of two, three, four, 

 etc. The amount of crystals being considered 

 sufficient to separate them, the matrass is sharp- 

 ly inverted, so as to cool and solidify the melted 

 sulphur in the neck. Thus the crystals are 

 separated from the rest of the sulphur, and 

 only remain suspended by their peaks. They 

 are transparent and remain so indefinitely; in 

 form they are octahedral and bear close resem- 

 blance to natural crystals. Measurement of 

 the angles has confirmed their identity. The 

 experiment is surer when two or three drops 

 of sulphide of carbon are added to the sulphur 

 before fusion; the phenomenon takes place, 

 however, independently of this admixture. By 

 this experiment of M. Schtitzenberger's it is 

 proved that melted sulphur crystallizes below 

 100 in octahedra of the fourth system without 

 the aid of any solvent. The facts will proba- 

 bly be turned to account in the study of the 

 formation of natural crystals. 



