128 SCIENTIFIC AMUSEMENTS. 



liquid may remain in the glasses. Dissolve a few grains of ferro- 

 cyanide of potassium in a pint of water, and put the solution into 

 a white glass water bottle or decanter. If the strengths of the 

 respective solutions are properly proportioned (which you can 

 easily adjust by making one or two preliminary trials) you will 

 find that on pouring out what appears to be plain water from the 

 decanter into the three glasses respectively, the first will apparently 

 be filled with blue ink, the second with a liquid somewhat 

 resembling brown sherry, and the third with milk. Be careful 

 not to allow any one to drink your fictitious beverages, as the taste 

 by no means equals the appearance, whilst one may easily be made 

 sick or ill with the metallic compounds, which are all more or less 

 injurious to swallow. 



A similar kind of effect may be produced in a variety of other 

 ways. Thus fill the decanter with a weak solution of per chloride 

 of iron to which a small quantity of sulphuric acid has been added, 

 and rinse out five wineglasses, one with solution of ferrocyanide 

 of potassium, another with a moderately strong solution of sulpha- 

 cyanide of potassium (a different compound) ; a third with a very 

 much weaker solution of the same salt ; a fourth with a strong 

 solution of carbonate of potassium (or instead sprinkle inside a 

 few grains of carbonate of sodium); and the fifth with a solution of 

 nitrate of barium. On filling up the five glasses from the decanter 

 the first will appear to be filled with blue ink, the second with 

 blood * or port wine (according to the strength of the solution) 

 the third with sherry (if the solutions are not too strong), the 

 fourth with champagne or ginger ale (on account of the efferves- 

 cence produced by the action of the sulphuric acid on the carbonate, 

 as in Expt. 99), and the fifth with milk, the white precipitate 

 being now due to the formation, not of ferrocyanide of zinc, as in 

 the former case, but of sulphate of barium. This kind of experi- 

 ment may be varied in a large number of ways, according to the 

 chemicals used; but in all cases it is unwise to taste the coloured 

 fluids. 



Expt. 128. To produce a Solid Mass by Mixing two Clear 

 Fluids. Make a strong solution of pearlashes (carbonate of 

 potassium) in one glass, and another of chloride of calcium in a 

 second; mix the two together, when a chemical change of double 

 decomposition will ensue, causing the precipitation of a solid sub- 

 stance essentially identical with chalk, termed car bonate of calcium, 



* Conjurors often use two sponges, soaked in solutions of perchloride of iron 

 and sulphocyanide of potassium respectively, for the purpose of apparently 

 producing blood in some of their illusions, the sponges being squeezed so as 

 to express the liquids, and cause them to mix together. 



