We trust after this the good housewife will feel jealous no longer, but rest satisfied that the home-made article, if less inviting and vivid in colour, is at least more wholesome. A simple test to discover the presence of copper in such articles is to place a bright knitting-needle in the vinegar, and let it remain there for a few hours, when the deleterious metal will speedily form a coating over it, dense or thin, according to the amount which exists. Wherever large quantities are found, it is wilfully inserted for the purpose of producing the bright green colour, but a small quantity may find its way into the pickles in the process of boiling in copper pans. Messrs. Crosse and Blackwell, the great pickle and preserve manufacturers in Soho, immediately they became aware, from the analyses of the _Lancet_, that such was the case, in a very praiseworthy manner substituted silver and glass, at a great expense, for all their former vessels. The danger arising from the introduction of this virulent poison into our food would not be so great if it were confined to pickles, of which the quantity taken is small at each meal, but it is used to paint all kinds of preserves, and fruits for winter pies and tarts are bloomed with death. The papa who presents his children the box of sweetmeats bedded in coloured paper, and enclosed in an elegant casket, may be corroding unawares the very springs of their existence. As a general rule, it is found that the red fruits, such as currants, raspberries, and cherries, are uncontaminated with this deleterious metal, but owe their deep hue to some red colouring matter, such as a decoction of logwood or an infusion of beetroot, in the same way that common white cabbage is converted into red by the nefarious pickle-merchant. The green fruits are not all deleterious in the same degree; there seems to be an ascending scale of virulence, much after the following manner:--Limes, gooseberries, rhubarb, greengages, olives--the last-mentioned fruit, especially those of French preparation, generally containing verdigris, or the acetate of copper, _in highly dangerous quantities_. The _Lancet_ publishes a letter from Mr. Bernays, F.C.S., dated from the Chemical Library, Derby, in which he shows the necessity of watchfulness in the purchase of these articles of food:--