FUERO  , a

Spanish term, derived from the Latin forum . The Castilian use of the word in the sense of a right, privilege or charter is most probably to be traced to the Roman conventus juridici, otherwise known as jurisdictions or fora, which in Pliny's time were already numerous in the Iberian peninsula . In each of these provincial fora the Roman magistrate, as is well known, was accustomed to pay all possible deference to the previously established common law of the district; and it was the privilege of every free subject to demand that he should be judged in accordance with the customs and usages of his proper forum . This was especially true in the case of the inhabitants of those towns which were in possession of the jus italicum . It is not, indeed, demonstrable, but there are many presumptions, besides some fragments of direct evidence, which make it more than probable that the old administrative arrangements both of the provinces and of the towns, but especially of the latter, remained practically undisturbed at the period of the Gothic occupation of Spain.l The Theodosian Code and the Breviary of Alaric alike seem to imply a continuance of the municipal system which had been established by the Romans; nor does the later Lex Visigothorum, though avowedly designed in some points to supersede the Roman Iaw, appear to have contemplated any marked interference with the former fora, which were still to a large extent left to be regulated in the administration of justice by unwritten, immemorial, local custom . Little is known of the condition of the subject populations of the peninsula during the Arab occupation; but we are informed that the Christians were, sometimes at least, judged according to their own laws in separate tribunals presided over by Christian judges; 2 and the mere fact of the preservation of the name alcalde, an official whose functions corresponded so closely to those of the judex or defensor civitalis, is fitted to suggest that the old municipal fora, if much impaired, were not even then in all cases wholly destroyed . At all events when the word forum 3 begins to appear for the first time in documents of the loth century in the sense of a liberty or 1 The nature of the evidence may be gathered from Savigny, Gesch. d. rom . Rechts . See especially i. pp . 154, 259 seq . 2 Compare Lembke u . Schafer, Geschichte von Spanien, i .

314;11 . 117. s Or rather forus . See

Ducange, s.v . 286 but is always much richer in hydrogen (of which it contains sometimes as much as 20%) and poorer in carbon monoxide (sometimes down to 20%) than Siemens gas ; generally it contains more of CO2 than the latter . The proportion of nitrogen is always less, about 5o% . It is therefore a more concentrated fuel than Siemens gas, and better adapted to the driving of gas-engines . It scarcely costs more to make than ordinary Siemens gas, except where the steam is generated and superheated in special apparatus, as is done in the Dowson.producer, which, on the other hand, yields a correspondingly better gas . As is natural, its properties are some way between those of Siemens gas and of water gas; but they approach more nearly the former, both as to costs and as to fuel-value, and also as to the temperatures reached in combustion . This is easily understood if we consider that gas of just the same description can be obtained by mixing one volume of real water gas with the four volumes of Siemens gas made during the blowing-up stage—an operation which is certainly too expensive for practical use . A modification of this gas is the Mond gas, which is made, according to Mond's patent, by means of such an excess of steam that most of the nitrogen of the coke is converted into ammonia (Grouven's reaction) . Of course much of this steam passes on undecomposed, and the quantity of the gas is greatly increased by the reaction C+2H20=CO2+2H2; hence the fuel-value of this gas is less than that of semi-water gas made in other ways . Against this loss must be set the gain of ammonia which is recovered by means of an arrangement of coolers and scrubbers, and, except at very low prices of ammonia, the profit thus made is probably more than sufficient to cover the extra cost .

But as the

process requires very large and expensive plant, and its profits would vanish in the case of the value of ammonia becoming much lower (a result which would very probably follow if it were somewhat generally introduced), it cannot be expected to sup-plant the other descriptions of gaseous fuel to more than a limited extent . Semi-water gas is especially adapted for the purpose of driving gas-engines on the explosive principle (gas-motors) . Ordinary producer-gas is too poor for this purpose in respect of heating power; moreover, owing to the prevalence of carbon monoxide, it does not light quickly enough . These defects are sufficiently overcome in semi-water gas by the larger proportion of hydrogen contained in it . For the purpose in question the gas should be purified from tar and ashes, and should also be cooled down before entering the gas-engine . The Dowson apparatus and others are constructed on this principle . Air Gas.—By forcing air over or through volatile inflammable liquids a gaseous mixture can be obtained which burns with a bright flame and which can be used for illumination . Its employment for heating purposes is quite exceptional, e.g. in chemical laboratories, and we abstain, therefore, from describing any of the numerous appliances, some of them bearing very fanciful names, which have been devised for its manufacture . (G .