A collection of small squares of sealing-wax would be cheaper, and might if duly verified by comparison with the porcelain standard be in many cases a useful instrument. Glass also might supply a suit of transparent colours of great interest. A complete collection of the enamel colours used for the mosaic work made at Rome would also be instructive. § Perhaps the most important advantage which such an Exposition can confer, is to instruct the consumer in the art of judging of the character of the commodity he is about to purchase. Besides the money we pay in return for the skill, labour, and capital expended in producing each article we purchase; a further, and often a very considerable sum is paid in order to assure us that it possesses those qualities which the vendor has asserted. This is called the _cost of verification_; in some cases, as in that of white sugar, it is very small, for almost every one can see by its external character the degree of goodness of that article. In other cases nothing less than a whole life spent in acquiring a knowledge of his subject, can be of any avail, as _in the case of the purchase of a field_. The verification of the fact that the vendor has really the right to sell it, can, in many cases, be arrived at only by a profound chancery-lawyer, and sometimes requires an expense even beyond the value of the field itself. When the purchaser has been convinced that he is no judge of the goodness of an article, he usually buys it at some shop having the reputation of selling only the best of the kind. In this case he justly pays a higher price to the vendor, who ought to be remunerated for his skill in selecting good articles from the manufacturer or merchant, and for his integrity in not taking advantage of the ignorance of his customer. It may be contended that it is cheaper for the purchaser to pay for the use of the skill and integrity of the vendor than to spend his own time in acquiring the same skill; and in many instances this is true. Still, however, the integrity remains to be paid for, and if simple and ready modes of verification were more generally known, a very large portion of this loss of time would be saved. In all those articles which are easily verified the retail price varies but little; whilst on those that are difficult to verify, the price of the same article, although apparently of the same quality, will be found to vary considerably at different shops.