A dozen papers relating to disease-prevention / by Cornelius B. Fox.

  • Fox Cornelius B. (Cornelius Benjamin) b, 1839.
Date:
1884
Catalogue details

Licence: Public Domain Mark

Credit: A dozen papers relating to disease-prevention / by Cornelius B. Fox. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    or others. On a liot summer's day my flask and a few biscuits were my usual companions, when circumstances took me away from home for many hours. I soon began to be aware that the contents of my flask underwent a sHght change in flavour, of a disagi'eeable character. As my senses are very acute, the change was not detectable by others. The taste becoming veryunpleasant, I threw aside my beautiful electro-plated .flask, and returned to a shabby old glass flask, protected by basket or wicker-work. Curiosity naturally prompted me to endeavour to ascertain if other electro-plated drinking-horns conferred on wines, etc., any disagreeable taste. I found, as the result of this inquiiy, that all of these flasks acted more or less in a similar manner. The next point that presented itself was as to the cause of this change. Knowing that electro-plated goods are composed of copper covered with a very thin coating of silver, applied with varying degrees of skill, I suspected that whilst using the flask, I was slowly poisoning myseK with the former metal. Ultimately I discovered that sherry which has been kept in an electro-plated flask finishes imequivocal evidence of the presence of copper, whilst a sample of the same sherry, sub- mitted to the same chemical tests, yields no copper. To deter- miue its presence or absence we should proceed thus :— 1. A little of the changed sherry is evaporated in a platinum dish to dryness, and to the ash is added a little dilute nitric acid. On leaving a strip of zinc in the acid for a few moments, it wiU be found that the platinum is coated with copper. After washing the dish, it is well to add a little liquor ammonise, which, whilst removing the copper, acquires a bluish tinge. 2. Whilst the evaporation is proceeding, 70 c.c. of the suspected sherry are poured into a small white evaporating dish, and a glass rod, which has been dipped in sulphide of ammonium, is introduced. If a black or brownish-black pre- cipitate or colom- is formed, which a drop or two of strong hydro- chloric acid cannot remove, more than one-tenth of a grain of copper or lead is present. 3. To enable us to distinguish between these two metals, a little of the altered sherry is poured into a test tube, and a solution of ferrocyanide of potassium is added. A chocolate- brown gelatinous precipitate or claret-coloured fluid (if the amount of copper is small) is produced, Avhich disappears on the addition of liquor potassae—a reaction which is characteristic of copper. When brown sherry is operated upon, or any wine possessing much colour, it is desirable to decolourize it with