The essentials of materia medica and therapeutics / by Alfred Baring Garrod.

  • Garrod, Alfred Baring, 1819-1907.
Date:
1877
Catalogue details

Licence: Public Domain Mark

Credit: The essentials of materia medica and therapeutics / by Alfred Baring Garrod. Source: Wellcome Collection.

    519/560 (page 483)
    •:■■-iSs^Xi *S*S2iF%* ' !ii!>*\ iS'i thtftU. ' ; ' ^Mraetie* may be employed instead of •V':. 1 ■ v v <ai Lr convenienee J of the numbers . '•.< '-^ti-netres contain ramestf I' j heailphniwuaei-i1^^ • * 0=180,^; :'A:;I' llt^oeimva-1 *£$&**** YOLUMETEIC SOLUTIOXS. 4s3 having half filled the flask with water, allow the salt to dissolve • then dilute the solution with more water until it lias the exact bulk of 10,000 grain-measures. The solution should be kept in an opaque stoppered bottle, iooo grain-measures of this solution contain i of an equivalent in grains of nitrate of silver for 17 grains). v ' Grammes and cubic centimetres may be employed instead of grains and grain-measures, but for convenience i of the numbers should be taken. 100 cubic centimetres contain of an equi- valent in grammes of nitrate of silver (or 17 grammes). This solution is used in testing the following substances : Acidum Hydrocyan]cum Dilutum, Potassii Bromidum, Sod® Arsenias (dry) When nitrate of silver is added to a solution of lyclrocyanic acid, to which an excess of soda has been added it gives rise to the formation of a double salt, consisting of one equivalent of cyanide of sodium and one equivalent of cyanide of silver (NaAgCy ) which is precipitated at first, but re-dissolved on agitation. When all the hydrocyanic acid is withdrawn in the formation of this double cyanide, nitrate of silver <uves rise to a precipitate no longer soluble; the appearance of thfs perm!! nent precipitate of oxide of silver is an indication that III the cyanogen is exhausted. The changes may be exhibited in the formula (AgN03+2NaCy=NaN03+NaAgCy2), and when no more cyanide is ^(WaiEo.3^J +H20). Hence it will be seen that each equivalent of nitrate of silver represents two of hydrocyanic acid. So that ,7 gm fns of nitrate of silver will correspond to h-7 x 2) £rran-tia L , , hydrocyanic acid. 5 4 (- 7 X 2) giains of absolute . - of JUif- s> -r ftlO> -Of* 0tef. ,1 . tk’lu> w ‘1l J