The preserving principle is, as I have already observed, invariable in its effects. Thus every loss I have sustained from any of the articles being spoiled, had no other cause than an erroneous application of the principle, or some negligence or omission in the preparatory process already pointed out. It sometimes happens to me even now, that my operations do not perfectly succeed; but no man makes experiments in any of the arts, or in any branch of natural philosophy, without being liable to disappointment. Nor can any one, therefore, who is employed in such a process as mine, flatter himself that he may not sometimes find his commodities spoiled from some defect in a vessel, or in the interior of a cork. But in fact, when due attention is given, these losses seldom take place. § VI. _The means of distinguishing among the Bottles or Jars, as they are taken from the Boiler, such of them as, from some neglect in the preparatory process, some accident, or the action of the fire, are in danger of occasioning a loss, or spoiling the substances enclosed in them._ When the operation is completed, of whatever kind it may be, I take the greatest care in my power to examine all the bottles and jars one by one, as I take them from the boiler. I have remarked in some, defects in the glass, as stars and cracks occasioned by the action of the heat in the water-bath; or by the tying, when the mouth of the vessel has been too weak. I have observed in others, a moisture round the stopper, or little spots near the mouth, from which I inferred that part of the substance enclosed had oozed out during the dilation or expansion produced by the heat of the water-bath: these are the two principal observations that usually occur to me: and whenever I observe either of these appearances on any bottle, I always set it aside, and make use of the substance immediately, that nothing may be lost. The first of the flaws pointed out, arises from the quality, and originally bad structure of the bottle; but the second may arise from any one of four causes:--1. From a bad cork; 2. from bad corking; 3. from the bottle having been filled too near the brim; and 4. from bad tying. A single one of these faults is sufficient to spoil a bottle; more easily, therefore, a complication of them.