CHEMISTRY. 



f UTAKATI-S. 



of mstcruli are used, U a tout-till* with a bent tube. 

 Pl. t. A cork U first tit tod in the 



Pneck : and a hole having been 

 i it, a glass tube, which 

 has been prerionsly bent into 

 the required shape, is then in- 

 troduced. The arrangement is 

 represented in the annexed 

 engraving (Fig. 2). When 

 Urgw quantities have to be used, a Florence flask, 

 8ttd with a bent tube, may be employed. These are 

 r^.t. _^. extremely useful for a great 

 .X^l variety of ehemieiil experiments. 

 ^^^ fl They are very cheap, and may be 

 ^^^ f\ cleaned by pouring into them 



.^r A \ some strong sulphuric acid to 



gT \ remove the oil, and, subso- 

 t* J qnently, washing them out with 

 vAf hot soda and water. The stu- 

 dent should provide himself with 



several of these, and various sizes of the test-tubes last 

 describe*!. They are both used for making solutions, 

 and a variety of other purposes. A test-tube may be 



held over a lamp by 

 means of a proper 

 holder ; but in the 

 absence of this, a 

 piece of brown paper 

 held round it, will 

 prevent the passage 

 of heat to the fin- 

 gers. Fig. -t repre- 

 sents the mode of 

 making hot solu- 

 tions after this plan. 

 Retorts, flasks, 

 <fcc., require a sup- 

 port to hold them over the flame of a lamp whilst being 

 heated. The ordinary retort-stand answers this purpose ; 

 flf . s. and one is easily made by fastening an 

 iron rod in a wooden foot, and twisting 

 round tho rod rings of iron wire of 

 various sizes. One of these stands is 

 represented in the annexe. 1 engraving 

 (Fig. 5). 



The application of heat is so frequently 

 required in chemical experiments, that 

 tho student must supply himself with 

 lamps for that purpose. Gas may be 

 so employed ; but tho most generally 

 useful instrument is the spirit-lamp, re- 

 presented in Fig. 6. Spirits of wine, or, 

 what is cheaper, methylated spirits, are 

 used as fuel. An ordinary cotton wick 

 is employed ; and a cap, which fits over 

 the wick-holder, is placed on it when 

 the lamp is not in use, so as to prevent 

 the loss of spirit by evaporation. 



A trough is required for tho purpose 

 of collecting gases. This may be an oblong tin box, 

 having a trsv at one end, on which gas jars can l>e 

 d. The tray is perforated 

 with holes, so that the gas 

 may pass through them into 

 the jars. A pneumatic trough, 

 as they are called, is repre- 

 sented in Fig. 7. In the ab- 

 sence of such an arrangement, 

 a basin, pan, or pail, will an- 

 swer every purpose. The gas 

 jars are mode of various sizes 

 and shapes ; two of which are 

 represented in Fig. 8. 

 The mode of using the pneumatic trough is as 

 follow* : Kill tho trough nearly full of water, and dip 

 the bottle or jar beneath the surface of the liquid. HO 

 that the whole of the air may be driven out. Th. n 

 raise the jar, with its open part downwards, and let that 

 rwt on the tray of tho trough. The jar will thus 



Flf.H. 



remain full of water, and, as the gas from a retort 



Hf.T. 



paanet into it, the water will gradually escape. The 

 following engraving illustrates the mode of unking 

 oxygen gas, a small furnace being used in place of the 

 spirit-lamp. A jar, when tilled with gas can be re- 

 Fur. . 



moved from the tray of the trough by passing 1 

 it a plate. This, by holding a little water, j 

 the escape of gas, and so retains the latter n t . 10. 

 inside the glass vessel. 



For many purposes, gas jars, open at both 

 ends, are required ; and when being filled with c 

 gas, the narrow end must be closed by means f \ 

 of a stopper or cork. Fig. 10 represents one 

 of these jars ; and inside it is a holder, useful 

 in experiments with oxygen ami chlorine. 

 The holder consists of an iron wire, with n 

 collar at one end, and a brass cup at the 

 other. The material is placed in the cup, 

 and, after being ignited, it is introduced into tli -. 

 gas jar. The student can easily make one of these, 

 after the pattern shown in the annexed engrav- FI*. 11. 

 ing. Gas-holders are very useful for holding 

 quantities of oxygen, itc. ; and one of the best 

 kind is that represented in Fig. 12. It consists 

 of a cylindrical metal vessel, having at the lower 

 part an opening, which can be closed by means 

 of a cap. At the upper part of the lower 

 cylinder a stopcock is placed, through which 

 the gas passes when it is in use. Between the 

 cylinder and the trough over it are two pipes, 

 fitted with stopcocks, through which water passes 

 from the trough, when the gas inside the holder 

 is required. These are filled by allowing water 

 to pass from the trough into the cylinder until 

 all air is driven out by the side stopcocks. All 

 the stopcocks are then to be closed, and the 

 bottom cap must be opened. The stem of a retort is 

 then inserted, from which the gas iir. 12. 



passes into the cylinder, driving out 

 tho water by the bottom hole. 

 When the holder is thus filled with 

 gas, the retort must be removed, 

 tho cap screwed on, and the upper 

 trough filled with water. One of 

 the stopcocks, between tho trough 

 ind the cylinder, may be opened, 

 through which the water will pass, 

 anil force out the gas through the 

 side stopcock. An india-rubber tube 

 is to be fitted to this, to conduct 



the gas to any place it may be re- 



quired. In making large quantities of oxygen, which 



