The difficulty and expense of verification are, in some instances, so great, as to justify the deviation from well-established principles. Thus it is a general maxim that Government can purchase any article at a cheaper rate than that at which they can manufacture it themselves. But it has nevertheless been considered more economical to build extensive flour-mills (such are those at Deptford), and to grind their own corn, than to verify each sack of purchased flour, and to employ persons in devising methods of detecting the new modes of adulteration which might be continually resorted to. 183. Some years since, a mode of preparing old clover and trefoil seeds by a process called doctoring, became so prevalent as to excite the attention of the House of Commons. It appeared in evidence before a committee, that the old seed of the white clover was doctored by first wetting it slightly, and then drying it with the fumes of burning sulphur, and that the red clover seed had its colour improved by shaking it in a sack with a small quantity of indigo; but this being detected after a time, the doctors then used a preparation of logwood, fined by a little copperas, and sometimes by verdigris; thus at once improving the appearance of the old seed, and diminishing, if not destroying, its vegetative power already enfeebled by age. Supposing no injury had resulted to good seed so prepared, it was proved that from the improved appearance, the market price would be enhanced by this process from five to twenty-five shillings a hundred weight. But the greatest evil arose from the circumstance of these processes rendering old and worthless seed equal in appearance to the best. One witness had tried some doctored seed, and found that not above one grain in a hundred grew, and that those which did vegetate died away afterwards; whilst about eighty or ninety per cent of good seed usually grows. The seed so treated was sold to retail dealers in the country, who of course endeavoured to purchase at the cheapest rate, and from them it got into the hands of the farmers; neither of these classes being capable of distinguishing the fraudulent from the genuine seed. Many cultivators, in consequence, diminished their consumption of the article; and others were obliged to pay a higher price to those who had skill to distinguish the mixed seed, and who had integrity and character to prevent them from dealing in it.