= Solution
TODO: Solutions d and e and their test observations are absent. Iodine and morphia are named testing targets, not reported positive findings.
\b[Neither <iodine> in $d$ nor <morphine> in $e$ is established.] “Morphia” is the historical name for <morphine>. The available task can nevertheless be explained as two distinct analytical investigations, using separate portions and reference preparations.
For $d$, first distinguish free <iodine> from <iodide>. A cool, freshly prepared <starch> solution gives a strong blue colour with accessible <iodine> under suitable conditions. Test the reagent by itself and beside a known <iodine> preparation, so that contamination or a failed reagent is not mistaken for an observation about $d$. The intense blue starch indication is documented in contemporary discussion of the 1864 <British Pharmacopoeia>.<Chemical News volume 9 (1864)>[p. 99, The British Pharmacopoeia, starch as an indicator for the first excess of iodine]{ref}
An absent direct blue response would not, by itself, exclude <iodine> present as <iodide>, or establish that the specimen contains no interfering material. If the task includes combined <iodine>, an appropriately controlled oxidation on a separate portion is needed to liberate testable <iodine>; the unoxidized and treated portions answer different questions. The response of the untreated specimen must not be confused with one deliberately produced by changing its chemical state. These are possible branches of the investigation, not observations supplied for $d$.
For $e$, use the period's chemical identity reactions as corroborating observations. The <British Pharmacopoeia by the General Medical Council (1864)> describes the response of hydrochlorate of morphia to <iron(III) chloride> and <nitric acid>: the former gives a blue indication under the specified conditions, and the latter an orange-red indication. The monograph is a reference for a defined material; it does not guarantee that every dilute or impure unknown will reproduce those colours.<British Pharmacopoeia by the General Medical Council (1864)>[Morphiæ Hydrochloras, Characters and Tests, pp. 93–94; primary monograph reproduced on PDF page 37 of the linked facsimile presentation]{ref}
Use separate portions for the two tests and include a <reagent blank> and a known <morphine> reference. Acidity, concentration and other coloured or reactive constituents can affect interpretation. A single colour should therefore be treated as preliminary evidence rather than a conclusive identification in an unrestricted unknown. An unexplained failure of the known reference would invalidate the comparison, while a coloured blank would indicate a problem independent of $e$.
A completed practical record would give the actual response of each sample, reagent and reference, followed by an appropriately qualified conclusion. \b[The reference behaviours explain the tests; they cannot supply the missing results for $d$ or $e$.]
Back to article page
