stance was, that I thought its amount too small to give satisfactory results. 10. In the silica, the apparent difference in the two analyses is considerable. From the method employed, and subsequent experience from other waters, in some of which I have found as much as 50 per cent. of silica, I am convinced that my estimation, if anything, is too low. With all possible care, some of the silica will attach itself so firmly to the vessel during the evaporation, that it becomes perfectly impossible to remove it completely by rubbing with water, or even with acids. This same cause would act still more to diminish its amount in Prof. SILLIMAN's analysis, where the portion precipitated, during the evaporation in the glass flasks, could not be removed by any mechanical means. That the actual amount of silica in the water analyzed by Prof. S., must have been greater, can easily be proved by his own experiments; for if we, from Table I., add together the carbonate of lime, the magnesia and the silica, they ought, together, to make up all the fixed insoluble ingredients; but in this way we only obtain 2.145 grains, while his direct estimation of the same, (see Table III. and his Report, page xvii.), yielded 3.69 grains, a difference of 1.54 grains. Allowing a fair proportion of this to be due to the too small estimation of the carbonate of lime and the carbonate of magnesia (see § 8), it leaves yet a difference for the silex in the two experiments, which is too great to be supposed to have been committed in that one ingredient, and shows that part of the difference must be due to the separate estimation of the whole insoluble ingredients. The amount of insoluble fixed ingredients calculated in the same manner from my analysis, gives it 2.9 grains. The average of the two above numbers of Prof. S., will give it 2.92 grains. 11. It has already been seen, that some great mistake must exist in Prof. HORSFORD's estimations of the amounts of solid ingredients in the different waters, making the Schuylkill water contain 35 grains of solid residue to the gallon. From the foregoing, it appears that his estimation of the relative proportions of fixed and insoluble matter, is equally erroneous. The main ingredients of the fixed residue of the Schuylkill water are formed of carbonates of lime and magnesia, with some silica, constituting the insoluble and greater part of it, (according to the above analysis, at least more than 50 per cent.). How Prof. HORSFORD can make it to be only 12 per cent., (0.0239 out of 0.1975, see the Boston Water Commissioners' Report to the City Council, page 33), is utterly inconceivable, more especially as it is evident, that he did not heat the residues to the expulsion of the car bonic acid from the lime, or that he means, by "insoluble after ignition," insoluble in acids; for he states expressly, that these amounts, "insoluble after ignition," "are, for the most part, carbonate of lime." 12. The amount of chlorohydric acid, and its equivalent of chloride of sodium, is almost identical in both analyses, the latter varying only 0.006 grain to the gallon. 13. The difference in the amount of sulphuric acid, though small by itself, is nevertheless considerable, when compared with its quantity. As estimated by me, from a portion of the residue (the same that was used for the estimation of the chlorohydric acid), it amounts to 0.302 grain per gallon. Prof. SILLIMAN estimated its amount by precipitation of the water during boiling, without previous concentration, to be 0.0245 grain per gallon, making a difference of 0.277 grain per gallon, and being less than one-tenth of the amount found by me. Calculated from the analysis in Table I., the amount is a little different (0.0376). It is therefore uncertain whether Prof. S. also estimated it from a part of the solid residue, as he makes no mention of it. If not, I should consider his method likely to give a too small result, for as the gallon, or 58,330 grain, can contain only .03 of a grain, the water contains only 1000 of its weight of sulphuric acid, which is rather too great a dilution for forming and collecting, completely, a precipitate, of however insoluble a nature it may be. 14. The amount of alkali in my analysis, is 0.448 grain to the gallon, in Prof. S.'s 1.041 grains to the gallon, making a difference of 0.593 grain to the gallon. Prof. SILLIMAN gives the whole as soda, not mentioning whether he tested it for potassa. Though I did not estimate its quantity, I convinced myself of its existence. Prof. S. also considers all the carbonate of soda to have been formed from the decomposition of crenates and nitrates, but I am confident that the water contains free alkaline carbonates, and that if it be evaporated to dryness in a water bath, and again treated with small portion of water and filtered, the concentrated solution, or the residue obtained from it, will show an effervescence with an acid; an experiment which, though uncertain whether performed with the residue from the Schuylkill water, I have performed with similar waters from the neighbourhood of Philadelphia. The slight alkaline reaction which I found on litmus paper, seemed also to indicate the existence of free alkaline carbonates. 15. In regard to the existence of nitrates in the Schuylkill water, it is an important observation of Prof. S., that by heating the residue, a distinct deflagration took place; though this would undoubtedly tend strongly to infer their existence, still it would be well to confirm this by collecting or observing the nitrous oxide gas given off at the same time. To me no such deflagration occurred; perhaps I did not heat the residue to a sufficiently high temperature, though I heated it considerably above the boiling point of water, and I am under the impression that it began to turn slightly brown on the edges. 16. It will thus be seen that, as a whole, the two analyses confirm each other considerably, and I believe that the following results may be derived from them in regard to the composition of the Schuylkill water, and the differences in it at the two different periods, having three years between them. The Schuylkill water, when settled clear, is a water of superior purity. Its amount of chlorine and sulphuric acid is too small to produce any sensible reaction under most circumstances. Its main characters it derives from its carbonates, more especially the earthy carbonates, which, if they were present in larger quantities, would give it the character of a hard water, and— In regard to a difference of composition, at the two different periods, that, 1. The amount of sulphuric acid varied less than 0.277 grain to the gallon (§ 13). 2. Chloride of sodium, less than 0.006 grain (§ 12). 3. The earthy carbonates less than 0.4, perhaps not more than 0.14 (§ 8). 4. The silica less than 0.32 grain (§ 10). 5. Organic matter less than 1 grain to the gallon (§ 6). 6. Total amount of solid residue less than 1.4 grains to the gallon. Dr. GIBBON, Dr. HARE and Prof. JOHNSON, also entered into some explanations relative to the character and variability of the Schuylkill water. After the conclusion of these remarks, Prof. HENRY made a further brief explanation of the objects of the Smithsonian Institution. After which, the Association adjourned, to meet this afternoon at 4 o'clock. Monday, September 25, 4 P. M. The Association met agreeably to adjournment. President, Wм. C. REDFIELD, Esq., in the chair. The Standing Committee made a report, recommending the appoint ment of a committee to superintend the publication of the proceedings of the present meeting, and nominated for that committee Dr. ROBERT W. GIBBES, of Columbia, S. C.; Dr. ALFRED L. ELWYN, of Philadelphia; S. W. ROBERTS, Esq., of Philadelphia; Prof. JAMES B. ROGERS, of Philadelphia; WM. S. VAUX, Esq., of Philadelphia; Prof. B. SILLIMAN, Jr., of New Haven. Which recommendation and nominations were, on motion, concurred in. The Standing Committee also recommended that 1000 copies of the proceedings of the Association be published in pamphlet form, and placed at the disposal of the Chairman of the Committee on Publication.-Adopted. The following resolution, in regard to the publication of the proceedings, was also adopted: Resolved, That copies or abstracts of all communications made, either to the General Association, or to either of the Sections, must be furnished by the authors, otherwise only the titles shall appear in the published proceedings. The Standing Committee offered the following resolution, which was, on motion, adopted. Resolved, That this Association highly appreciate the object of Prof. GERMAIN, in collecting the fossils of the Greensand of New Jersey, and that the Society will, by every means in its power, encourage him in the same. The following gentlemen, having been duly nominated for membership, by the Standing Committee, were unanimously elected members of the Association, viz: ALGERNON S. ROBERTS, Esq., of Philadelphia; Dr. B. B. BROWN, St. Louis, Mo.; Dr. GERARD TROOST, Nashville, Tenn.; LEWIS TROOST, Esq., Nashville, Tenn.; Prof. A. GUYOT, of Cambridge, Mass., and JOHN E. THOMPSON, Esq., of Philadelphia. Prof. HENRY, on behalf of the Standing Committee, offered the following resolution, which was adopted: Resolved, That the thanks of the Association be tendered to Prof. JAMES B. ROGERS, for his kind attention to the convenience of the Association while holding its Sectional and General Meetings in the Chemical Lecture room of the University. On motion of S. W. ROBERTS, Esq., it was— Resolved, That the thanks of this Association are due, and are hereby respectfully tendered to the Trustees of the University of Pennsylvania, for the liberality with which they have given to the Association, the use of the halls of both the Collegiate and Medical Departments of the University. Prof. W. R. JOHNSON offered the following resolution, which was adopted : Resolved, That the thanks of the Association be presented to the Chairman of the last Annual Meeting, for the able and eloquent address delivered before the Association at its present session; and that he be requested to furnish a copy thereof, for publication in the proceedings. The Secretary read the following letter from Prof. TUCKER, which was ordered to be entered on the minutes : Philadelphia, September 25, 1848. Sir,-Unable to leave my room, from an attack of bronchitis, I beg leave to propose what I had wished to submit this morning in person. I have been long desirous of seeing a general Statistical Society in the United States, and last year invited, through Hunt's Magazine, a meeting in this city for that purpose. The plan was very favourably responded to by some; but their number was not sufficient to justify the immediate formation of such a society. It was then suggested, that all the purposes of such a society might be attained by a Section of this Association, appropriated to statistics and political economy. I accordingly hastened on to the meeting, from Virginia, where I was on a visit, for the purpose of proposing such a Section, and, in my journey, caught the cold which now disables me. I will not waste the time of the Association in dwelling on the advantages of statistics. They are known to be auxiliary to all the sciences that are not demonstrative, and to furnish materials for those which are. They are particularly valuable in the United States, where changes are more rapid than elsewhere; and where, from the extent of our country, enumerations are more difficult. It may further recommend such a Section, that it will tend to make more of the proceedings of the Association intelligible and interesting to the public generally, and thus further the liberal and patriotic views of the Association; and though I do not belong to the class of utilitarians, but regard every species of knowledge valuable for its own sake, it cannot be a matter of indifference, that the pursuits of science, as those of statistics and political economy, have a direct bearing on the common concerns of life-lastly, in favour of such a Section, the Institution in England, which has served as our prototype, has a Section |