25;8 OK PRUSSIC AC»». 



solid, though immersed in the prussic >cu1.. If, an th« 

 contrary, a certain quantity of water liav€ passed oyer, two 

 very distinct strata of liquid will- be obtained ; the lov»^r, uij 

 aqueous solution of muriate of lime ; the upper, prus$ip 

 acid. This acid is commonly a little coloured in the first 

 phial. To rectify it, as goon as you think proper to termi- 

 pate the distillation* take out the tu^e communicating witl? 

 the retort ; stop the aperture by which it entered tiie phialj; 

 and, after ;re moving the frigoritic mixture, that snrroundc4 

 the latter, heat it vBtr-jj gently, either by njcans of a water- 

 bath or cl-mrcoai, so as not to raise thetemperatureijLboi'e 

 30* or ao** [66° or..,S5* F.]. • When this distillation j^' 

 finished, take away the first phial ; and, after the prussip 

 acid has remained a few hours in contact with the muriate 

 of lime in the second phial, pass, it over into the third,, by 

 means. of a gentle heat.. The rectification is then fini-^hed. , 

 Propert.ipsof / Prussic sfcid thus obtained i« a coiourless liquid, as cleaj 

 pure prussic as water. lis taste,; at first cool, soon becomes acrid an^ 

 \- '•:''■ • irritating. Though rectified several times over <-halk, it 

 faintly reddens litmus paper; but the blue colour returns, 

 as the acid evaporates. Its density at 7° [44'6° F.] is 

 l,ts great vola- P'7058J. .Its volatility is very great, fur it boils at SO'o* 

 'il'ty. ^-(j.-o p J . .^^ ^^jo ^^qo jr^-j jj. supports a column of mercury 



of q-38 met. [14-95 inches] ; and at 20'' [68* F.] it quintu- 

 ples the bulk of the air or gasses, %vith which it is mingled. 

 This property renders the employ of the apparatus I have 

 described indispensable; for, if it were poured froui one 

 vessel to another in the open air, a very large quantity would 

 be lost. This property also explains why it haa been said 

 by some chemists, that prussic acid may be obtamed in the 

 state of a permanently elastic fluid. ^ .. 



freezing Prussic acid exposed to a frigorific mixture cf two parts 



point. j(,g mj^j Q,-|^ ggjj. constantly congeals, and frequently as- 



sumes a regular figure. I have sometimes seen crystals af 

 this acid resembling those of fibrous nitrate of ammonia. 

 It remains solid at a temperature of — 15° [5" F.], but above 

 this point it lii^ueties. 

 Singulnrphe- The great volatility of this acid, and its congelation at 

 - —-15° [5° F.], occasion it to exhibit a nemarkable phenome- 

 , non, Ifu single drop be exposed to theair atthecxticmity ofa 



/ 



/(omeiion. 



