177 X1X.-On the Action of Boracic Acid upon the Carbonates of the Alkalies and Alknline Earths. BYCUARLES L.BLOXAM. BEINGengaged in the search after a direct method of valuing commercial samples of crystallized boracic acid I made several experiments in order to ascertain whether the amount of that acid could be inferred from the weight of carbonic acid which the sample was capable of expelling from carbonate of soda. Finding that boracic acid always expelled at a high tem- perature more than a single equivalent of carbonic acid and that the numbers obtained were not concordant I abandoned this method of estimating the boracic acid. My attention was recalled to this subject by the “Researches on Silica” of Colonel Philip Yorke,” in which the author has shown that silicic acid is capable of expelling a greater weight of carbonic acid from carbonate of soda than from carbonate of potassa and still more from carbonate of lithia.Colonel Yorke also stated that boracic acid (in the form of borax) afforded results arralogous to those given by silicic acid but that the num- bers obtained did not accord well together. I then resumed the examination of the action of boracic acid upon the carbonates of the alkalies and alkaline earths; and since a paper read very recently at one of the Society’s meetings has awakened an interest in the subject I beg to lay my results before the Society in the hope OC receiving some suggestion which may help to explain them and may afford me some guidance in con-tinuing the inquiry.Action of Boracic Acid upon the Alkaline Carbonates at 212’ F. In these experimen,ts crystallized boracic acid was employed which had been precipitated from solution of borax by hydro- chloric acid purified by several crystallizations and dried in vacuo over sulphuric acid. The carbonate of potassa was employed in the fused state and the carbonate of soda sometimes in powder sometimes in fused fragments. * Phil. Tranw 185i p. 533. VOL. XII. B ULOXA31 ON 'I'IfK AC'PIOX OF The boracic acid and the alkaline carbonate were dissolved iii a few drachms of water in a platinum dish the solution evaporated to dryness in the water-bath and the residue dried in the water- oven till its weight ceased to vary appreciably.It was then dis- solved in water arid the residual carbonic acid determined by the method of Fresenius and Will. The results are contained in the followiiig tables in whicli tlie equivalent of anhydrous boracic acid (BOJ is taken as = 34.9 the equivalent of carbonic acid as = 22 of potassa = 47 of soda = 32 of lithia = 14.5. Action of Boracic Acid 018 Curbonate of Potussa at 212". One equivalent (349) of boracic acid taken in each case. No. Carbonate of potassain equivalents Carbonic acid expelledin equivalents. I . . 0.33 . . 0.33 2 . . 0.56 . 0.39 3 . . Oa84 . . 0.39 4 5 . . . . 1*!)3 1.ox . . . . 0.31 0.29 6 . . 2.90 . . 0.14 It hence appears that when three equivalents of boracic acid were employed to decompose one equivalent of carbonate of potassa the whole of the carbonic acid was expelled at 212"F.; that when the carbonate was increased a somewhat larger pro-portion of carbonic acid was expelled until the carbonate arnoiinted to nearly oiie equivalent When nearly two equivalents of car-bonate of potassa were employed rather less carbonic acid was expelled than when only one-third of an equivalent had been taken and when nearly three equivalents of carbonate of potassa were employed for one equivalent of boiwic acid not half as much carbonic acid was expelled.The smaller quantity of carbonic acid expelled in experiments 4 5 and 6 might of course be accounted for by the retention of carbonic acid in combination with the excess of carbonate of potassa but on cndeavouriiig to makc a corrcction for this I fouud that the qwwtizies of carbonic acid arid vater retained by a given weight of carbonate of potilssa at 212' F.were far from constant.* It mas not possible therefore to assign a formula to any of the residues saw that of experiment 1 which would be repre- sented as K0.3B0 with 4.3 eqs. of water.? Action of Boracic Acid on Carbonate of Soda at 212'. One equivalent (3$9) of boracic acid taken in each case. NO. Carbonate of soda in equivalents. Carbonic acid ex- pelled in equivalente. 7 . . 0.33 . . 0.33 8 . . 0.51 . . 042 9 . . 1.17 . . 0.43 10 . . 1-24! . . 0.52 11 . 1.44 . . 0.55 12 - . 3-53 . . 066 These results are directly opposite to those obtained with car- bonate of potassa for the quantity of carbonic acid expelled increases progressively though not nearly in the same ratio with the quantity of carbonate of soda employed.Here also however we find that the whole of the carbonic acid is expelled when three equivalents of boracic acid are allowed to act upon one equivalent of carbonate of soda. * Three experiments were made in which weighed quantities of fused carbonate of potasw were dissolred in water the solution thoroughly saturated with carbonic acid evaporated to dryness on the water-bath and dried in the water-oven till the weight was nearly constant ; the mass was then dissolved in water and the carbonic acid determined by Fresenius and Will's process. The composition of the residue was-J. IT. 111. Potassa .. 1 eq. . 1 eq. . 1 eq. Carbonic acid . 1.35 eq. . 1-18cq. . 1.18 en Water . . 1-01 eq. . 1'10 eq. . 1-24 eq. On dissolv'ng 22.16 grns. of fused carbonate of soda in water and treating it in exactly the same way 21.10 grns. of the carbonate were obtained showing that in this case no carbonic acid and water hail been retained. + A crystallized terborste of potsssa was obtained by Laurent c0ntainir.g 3 eqq ofwater. N3 BLOXAM ON THE ,wrmN OF Having proved by direct experiment that carbonate of soda was not capable of retaining any excess of carbonic acid at 21ftoF. I was enabled to calculate the compositioii of the borates of soda formed in these experiments and found that except in euperi- ment 11 a definite formula might be assigned to them; thus:- No.7 gave 2 (Na0.3B0,) + 7H0. 8 , 3 Na0.7B03 + 9HO. 9 , 3 ATa0.7B0 + 6H0. 10 , NaO.2B0 + 4*3HO. 12 , 2 Na0.3B03 + 66HO. Action of Boracic Acid upon the Alkaline Carbonate4$at a dtdl red heat. In these experiments the materials were heated in platinum crucibles over the flame of an ordinary argand gas-burner fur-nished with a copper chimney about six inches high and supplied with as much gas as it could burn without smoking. The boracic acid was employed sometimes in the crystallized state sometimes after having been dried in the water-oven.* The alkaline carbonates were powdered and mixed with the boracic acid in the crucible. The mixtures were weighed at con- siderable intervals until their weight had ceased to vary more than a few hundredths of a grain.The carbonic acid expelled was ascertained by deducting the calculated amount of water from the total loss of weight. No concordant numbers were obtained by decomposing car- bonate of potassa with boracic acid at a dull red heat; but it was proved that less than one equivalent of carbonic acid was expelled by an equivalent of boracic acid even when a large excess of car-bonate of potassa was employed. * Finding that the formula of boracic acid dried at 212' was given by Gmelin upon the authority of Berzelius as 3H0.2B0 I dricd 30.95 grns. of the pure crystallized mid in the water-oven ti11 its weight was constant (which required about twelve hours) when it had lost 9.17 gms. or 29.62 per cent. The formula H0.B03 would require a loss of 29.08 per cent.which is sufficiently near to the experimental result the djfferencc being due to the slight volatilization of the acid. The above formula of Berzelius would require a loss of only 21.8 per cent. It will be seen that several of the experiments detailed in this paper confirm the formula HO.RO for boracic acid dried at 212". Action of Boracic Acid upon Carbonate of Soda at a dull red heat. One equivalent (349) of boracic acid taken in each case. No. Carbonate of soda Carbonic acid ex-in equivalents. pelled in equivalenta. 13 . . 1.24 . . 1.02 (3H0.B03) 14 . . 1-24 -. 1.03 (HO.BO,) 15 * * 1-24 . . 1-07 (3H0.B03) 16 . . 1.24 . . 1.02 )) 17 . . 1.50 . . 1.00 , 18 .. 2-20 . . 1.01 (HO.BO,) 19 . . 2.90 . . 1.00 (3HO.BOJ 20 . . 3.10 . . 1-05 ) 21 . . 3-10 . . 1.02 , 22 * . 3.10 . . 0.99 , 23 . . 3.10 . . 1.01 , 24 . . 3.10 . . 1.00 ) Mean of 12 experiments 1.018 In these cases the mixture had never fairly fused but had merely fri tted together. At a dull red heat then hydrated boracic acid expels one equivalent of carbonic acid from carbonate of soda and it cannot fail to be remarked that this result is uniformly obtained notwitb- standing the great variation in the proportion of carbonate of soda employed. It appeared probable that the amount of boracic acid con-tained in a commercial sample might be inferred from the quantity of carbonic acid expelled from carbonate of soda at a dull red heat; but it was found that the borscic acid then dis- placed more than a single equivalent of carbonic acid the escape of the latter being facilitated by the presence of ammoniacal salts in the crude boracic acid.Action of Boracic Acid upon Carbonate of Lithia at n dull red heat. One equivalent (34~9)of boracic acid taken in each case. NO. Carbonate of litliia in equivalents. Carbonic acid ex-pelled in equivalents. 25 . . 3.47 . . 2.53 26 . . 3.07 . . 2.42 The boracic acid and the carbonate of lithia were both em-ployed in the fused state. Anhydrous boracic acid is able to expel 24 eqs. of carbonic acid from carbonate of lith ct (z dvll red heat. Action of Boracic Acid upon the Alkaline Carbonates cf fs Wpit red heat.The materials were fused in platinum crucibles over a Solly's gas-furnace for ten or fifteen minntcs then weighed and again ignited for five or ten minutes until the weight did not vary in any considerable degree. A few preliminary experiments were made to ascertain the effect of this temperature upon the separate re-agents; and since this has of necessity a very important bearing upon the results it may be desirable to refer to the experiments upon boracic acid since some doubt might be entertained of its resistance to so high iltemperature. 30.95 grns. (+ eq.) of crystallized boracic acid were heated to dull redness over an argand gas flame when they lost 14.13 grns. of which only 13.5 grns. would be water the remaining 0.63repre-senting the volatilized boracic acid (3.61 per cent.of the dry acid employed). 16-82grns..of vitrefied boracic acid thus obtained were heated for ten minutes in EL loosely covered platinum crucible over the gas furnace when they had lost 0.21 grn. (1-24per cent.) When again heated for ten minutes in the open crucible bubbles were seen to form within the mass and a further loss of 0.29grn. mas perceived. 5.99 grns. of well vitrefied boracic acid taken from the stock employed for the following experiments were very strougly ignited over the gas-furnace in a covered crucible for five minutes when the loss amounted to 0.14 gm.,or 2.33pcr cent. When again BORACIC .icm ON THE CARBONATES &c. 183 heated for five minutes it suffered no further diminution; ignited a third time for seven minutes it had not lost though a fourth ignition for five minutes caused a loss of 0.02 grn.On igniting for five minutes in the open crucible the loss was 0.02 grn. and in the next five minutes 0.04 grn. These numbers lead to the inference that even supposing the boracic acid to be volatilized to the same extent in the presence of an excess of an alkaline carbonate the results will be but slightly vitiated ; for taking the whole loss in twenty minutes’ ignition in the first experiment it would represent only +-of an equivalent of carbonic acid for each equivalent of boracic acid. I also convinced myself that neither carbonate of potassa Dor carbonate of soda suffered any material diminution of weight at this temperature.The behaviour of carbonate of lithia mas very different. The carbonate of lithia employed was carefully tested for all impurities except potassa and soda the absence of any material qurtn tities of these being inferred from the circumstance that 5 grns. of the carbonate when decomposed by sulphuric acid gave 7.34 grns. of sulphate of lithia representing 4.91 grns. of the carbonate. The carbonate of lithia was dried in an air-bath at about 300’ F. until its weight was constant. 12-74grns. of the carbonate were strongly ignited over the gas furnace in a covered platinum crucible until the weight did not vary more than 0.09 grn. The loss amounted to 8.38 per cent. 12.66 gms of the carbonate lost 1-05 or 8.29 per cent.13.54 gms. lost 1.14or 8.41 per cent. 5-53 grns. of carbonate of lithia ignited till its weight did not vary more than 0.01 grn. after five minutes’ ignition had lost 0.83 or 15.0 per cent. The ignited mass treated with sulphuric acid gave 7.94 grns. of sulphate which would correspond to 5-317 grns. of carbonate of lithia or 0213 grn. less than was originally taken and 0.617 gm. more than if the mass after ignition were pure carbonate of lithia. The ignited mass must therefore have contained uncombined lithia the carbonic acid having been partially expelled. The loss of lithia would be accounted for by its volatilization during the repeated ignition. 13.14 gms. of carbonate of lithia lost 1-53or 11.6 per cent.13.2 gms. lost when ignited till it absolutely ceased to diminish after five minutes ignition had lost 1.34 or 10.15 per cent. 158 gms. of carbonate of lithia ignited till the variation did not exceed 0.01 had lost 10.70 per cent. It was dissolved in water and decomposed by an excess of chloride of barium; the liquid filtered from the carbonate of baryta was strongly alkaline both to litmus and turmeric indicating the presence -of lithia in an uncombined state. On treating the original carbonate of lithia in the same way the filtrate was very feebly alkaline to litmus and not at all to turmeric. From these experiments it is evident that the carbonate of lithia is partially decomposed by a bright red heat but that only a fraction of the carbonic acid can be thus expelled a limit being reached in every experiment at which the retaining power of the lithia was in equilibrium for that temperature with the tendency of the heat to expel the carbonic acid.The maximum amount of loss it will be observed was 15 per cent. which occurred in ignition for twenty-five minutes. This is only onenfourth of the total amount of carbonic acid (60.02 per cent.) which the carbonate of lithia contains To diminish as far as possible the errors arising from this decomposition of' carbonate of lithia the carbonate used in the following experiments was always ignited at the temperature of the experiment until its weight cesscd to vary materially in periods of five minutes before adding the boracic acid.Action of Boracic Acid upon Carbonate of Potassa at a bright red heat. One equivalent (34.9)of boracic acid taken in each case. No. Carbonate of potamin equivalents. Carbonic acid ex- pelled in equivalents. 27 . . 1-23 . 0 1.08 28 . . . 1.27 . . 1.08 29 . . 2.60 . . 1.11 30 . . . 1.63 . . 1-12 31 . . . 1.73 . . 1-15 32 . . 1.73 . . 1.22 33 . 1-75 . . 1.14 34 . . 1.77 . . 1.18 35 . . 1.83 . . 1.14 36 . . 2.441 . . 1.24 37 . . 2.75 . . 1-20 38 . . . 2*77 . . 1-24 39 . . 2.81 . . 1.23 40 . . 3-18 . . 1.21 41 . . 3.53 . . 1.23 42 . . 3.69 . . 1.26 Mean of 16 experiments 1.17 The boracic acid and the carbonate of potassa were both employed in the fused state. An examination of this table shows that at a bright red heat boracic acid expels somewhat more than one equivalent of car-bonic acid from the carbonate of potassa and that the amount of carbonic acid expelled usually increases with the proportion of alkaline carbonate taken though to a comparatively slight extent the minimum being 1.08 eqs.of carbonic acid when 1.25 eqs. of carbonate of potassa were employed and the maximum 1.26 eqs. of carbonic acid for 3.64 eqs. of carbonate of potaasa. It was not ditficult to obtain a nearly constant weight in these cases one or two weighings being generally found to suffice if the mass was heated at first for about fifteen minutes and after weighing for periods of five minutes. The fused masses when cool appeared to be composed of delicate prismatic crystals of a fine blue colour for which I was unable to assign a cause.BLOXAM ON TI1E .\CTlON OF Action of Boracic Acid upof2 Carbonate qf Sodit at a bright red heat. One equivalent (34.9)of boracic acid taken in each case. No. Carbonate of soda in equivalents. Carbonic acid expelled in equivalents. 43 . 1-50 . 1.48 (3H0.n03)* 44 . 2.01 . 1-88(HO.BO,) 45 . 2.02 1.81 , 46 . 2.20 . 1.95 47 . 2-28 . 1.88 (Bb3) 48 . 2.90 . 1-89 (3H0.B03) 49 . 3.10 . 1.73 9 50 . 3-20 . 2.04 , 51 52 53 . . . 3.10 3.39 4.40 * . . 1.93 1.85 2.22 (HO.BO,)(G,) 54 . 5.41 . 2-34 (BO,) 55 . 5-44 . 2-52 , 56 . 5.58 . 2.31 , The experiments numbered 44 46 49 50 51 52 and 53 were made in a muflle the rest over the gas-furnace. * The borate here formed would have the composition 3 Na0.2B0 ; and accord- ing to amelin this aalt was obtained by Arfvedson in the fusion of borax with carbonate of soda when each atom of borax expelled two atoms of carbonic acid.Three experiments which I made by fusing borax with exceas of carbonate of soda in a hot muffle agreed very nearly with the slipposition that three atoms of car-bonic acid were expelled by each atom of borax thus producing a borate of the formula 2Na0.B03. It will be seen that this accords with the general result of the experiments made with free boracic acid viz. that each atom of the acid may expel two atoms of carbonic acid thus combining with two atoms of soda. In some analyses of samples of commercial boracic acid by this nietliod in which forty four parts of carbonic acid expelled from the carbonate of soda were taken to represent 34-9 parts of BO, the percentage of boracic acid agreed very c*’osely with that obtained by determining all the other constituents of the samples separatc‘y but the circum- stance that a large proportion of carbonic acid may be expelled by samples con- taining a small pelcentage of boracic acid in coascquence of the increase in the proportion borne by the carbonate of soda to the acid renders this method too uncer- tain except in casca were the percentage of horacic acid ia already approximately known.BORACIC ACID ON THE CARBONATES &C. 187 In the experiments numbered 46,49 and 52 the residual car-bonic acid was determined and found to confirm the result inferred from the loss of weight proving that no appreciable volatilisa?,ion of horacic acid had taken place.Thc fused masses weregreyish white never blue as in the cases where carbonate of potsssa liad been employed. Tlie difficulty of obtaining a constant weight in these experi- ments was very remarkable as many as eight or ten weighings being often found necessary. It will be noticed that the increase of the amount of carbonic acid expelled according to the proportion of carbonate of soda employed is very much more marked than in the case of carbonate of potassa the rnininum being 1.48 eqs. of carbonic acid expelled from 1.50 eqs. of carbonate of soda and the maximum 2.52 eqs. of carbonic acid from 5*44eqs. of carbonate of soda.The amount of carbonic acid expelled by boracic acid from carbonate of soda at a bright red heat may therefore be said to ratige between 13 and 2 eqs. though in the majorityof the above experiments it approached more nearly to 2 eqs than to either of these limits. The masses obtained in these fusions were always very deli- quescent and far more caustic to the taste and toiich than car- bonate of soda. Action of Boracic Acid upon Carbonate of Lithia at a bright red heat. One equivalent (39.9)of boracic acid taken in each casc. E0. Carbonate of Lithia Carbonic acid expelled in eqiiiralent8. in cquivalents. 57 2.98 . . 2-47 58 3.07 . . 2.66 59 3.47 . 2-70 60 3.50 . . 2.53 61 5-10 . . 2-45 Mean of 5 experiments .. 2.66 The results with carbonate of lithia are seen to be nearly as constant as thosc with carbonatc of potassa rtrid it was evcn 188 BLOXAM ON THE Ac'rioN ov easier to obtain a constant weight in the case of carbonate of lithia. It appears then that at a bright 'red heat boracic acid is able to expel 24 eqs. of carbonic acid from carbonate of lithia a result which agrees with that obtained at a dull red heat. Action of Boracic Acid upon the Carbonates of Buryta and Strontia. Pure precipitated carbonate of baryta is not materially affected by the heat of the gas-furnace as the following experiments prove :-14% grns. of carbonate of baryta ignited in a covered crucible for ten minues had lost only 0.04 gr. 14.42 gms. ignited very strongly for fifteen minutes had lost only 0.11 grn.Carbonate of' strontia is as would be expected decomposed to a greater extent . 15*88 grns. heated for five minutes over the gasfurnace had lost 0.25 p.; on heating again for five minutes it lost 0.02grm. Total loss 1.7 per cent. 11.84 grns. lost in four successive periods of five minutes 0.15 0.10 0.18 and 0.17 gm. Total loss 5.07 per cent 12'43 grns. lost in three successive periods of five minutes 0.29 0.16 and 0.05 gm. Total loss 4-34per cent. It will be seen however that the decomposition of carbonate of strontia by heat will not materially affect the general result of the experiments for taking even the greatest amount of loss in the above experiments it would represent only 3.74 of carbonic acid (about + eq.) lost by one equivalent (73*8) of carbonate of strontia.ACTION OF BORACIC ACID &C. Action of Boracic Acid upon Carbonate of Baryta at a dull red heat. One equivalent (349) of boracic acid taken in each case. Carbonate of baryta Carbonic acid expelled NO. in equivalents (1 eq.=98'6). in equivalents. 62 0 2.82 . 196 63 . 3.00 . . 2.15 64 3.65 . . 1.92 Mean of 3 experiments . . 2.01 In No. 63 the hydrated boracic acid dried at 212" was em- ployed; in the other cases crystallised acid was taken. At a dull red heat boracic acid expels 2 eqs. of carbonic acid from the carbonate of baryta At a bright red heat. NO. Carbonate of baryta Carbonic acid expelled in equivalents. in equivalents.65 . . 2-82 . 2.56 (3H0.Bo3) 66 . . 3.87 2.42 (BO,) 67 . . 2-94 . 2.56 (BO,) 68 . . 3-00 . 2.60 (HO.BO,) 69 . . 3.01 . 2.45 (BO,) 70 . . 3.04 . 2.44 (BO,) 71 . . 3.22 . 2.47 (BO,) 72 . 3.50 . . 2-56 (3H0.B03) 73 . . 3.65 . 2-70(3H0.B03) Mean of 9 experiments . 2.53 The fused masses obtained here had many of the properties of caustic baryta becoming heated when moistened with water which partially dissolved them yielding powerfully alkaline solu-tions which deposited carbonate of baryta when exposed to the air. In the experiments with carbonate of baryta it was remarkably easy to obtain a constant weight but I found that no advantage could be taken of this in the valuation of commercial boracic acid since the ammonia and other volatile matters favour the escape of a larger quantity of carbonic acid.VOL XII. 0 RLOXAM ON THE It appears therefore that boracic acid expels 29 eqs. of carbonic acid both from carbonate of baryta and from carbonate of lithia at a bright red heat. Action of Boracic Acid upon Carbonate of Xtrontia at a dull red heat. One equivalent (349)of boracic acid taken in each case. Carbonate of strontia Carbonic acid expelled NO. in equivalents (1 eq. =73'8.) in equivalents. 74 . . 3.67 . min. 2.37 (SHO.BO,) 75 . . 3.76 . . 2-52 (HO.BO,) 76 . . 4.78 . . 2-61 2> 77 . . 6-65 . . 2-40(3H0.B03) 78 . . 9.00 . . 2.62 9 Mean of 5 experiments max. 2.50 At a dull red heat then hydrated boracic acid expels 24 eqs.of carbonic acid from the carbonate of strontia. In consequence apparently of the difficulty of fiising the borate of strontia it was found that no uniform results could be obtained by igniting fragments of glassy boracic acid with precipitated car- bonate of strontia; it was necessary to employ the boracic acid in the hydrated state and to mix thoroughly with a glass roil> after-wards drying at a gentle heat before igniting over the gas- furnace. At a bright red heat. No. Carbonate of strontia Carbonic acid expelled in equivalents. in equivalents. 79 3.67 . 2-90 80 3-76 . . 2.92 81 3.76 . . 3.03 82 4.78 . min. 2-86 83 6.65 max. 3-18 84 9.00 . . 3.14 Mean of 6 experiments .. 3*00 It was rather more difficult to obtain a constant weight in the case of carbonate of strontia than in that of carbonate of baryta. ACTION OF BORACTC ACID &C. It may be remarked that there is just half an equivalent more carbonic acid expelled from each of these last carbonates at a bright red as at SL dull red heat. From the experiments above recorded I should infer (though the results in the case of soda at a bright red heat are somewhat doubtful) that the quantities of carbonic acid expelled by boracic acid at a dull red heat from the caybonates of soda lithia baryta and strontia respectively are approximately in the ratio of the numbers 1 2$ 2 and 2+ and that the quantities of carbonic acid expelled at a bright red heat from the carbonates of potassa soda lithia baryta and strontia respectively are approximately as the numbers 1 2 24 and 3.What explanation can be given of these results ? It can hardly be supposed that there are four different equivalent weights to be assigned to boracic acid as representing the quantities required to displace a given amount of carbonic acid from its combinations with these direrent bases. It appears far more reasonable and far more in harmony with our knowledge of the chemical relations existing between these bases and more particularly of their relations to carbonic acid to attribute the progressive increase in the quantity of carbonic acid evolved to a corresponding decrease in the chemical attraction for that acid evinced by the several bases in question.In each case the decomposition may be supposed to proceed until the tendency of the borate which has been found to take up an additional quantity of base is in a state of equilibiiuni with the chemical attraction existing between that base and the car- bonic acid. Thus in the case of carbonate of potassa the monoborate of potassa (KO.BO,) which is formed at a bright red heat has only just so much attraction for an additional quantity of potassa as is counteracted by the opposing attraction of the potassa for the car- bonic acid whilst in the case of carbonate of strontia the attrac- tion between that base and the carbonic acid is only sufficient to counteract the tendency of the compound 3Sr0.B03to take up an additional quantity of strontia.If this were the true explanation it might be expected that boracic acid which had already been fused with an excess of carl3onate of potassa would still be able to expel carbonic acid from carbonate of soda or of lithia; for allowing the KOaBO a certain attraction for an additional amount of base it will be 02 BLOXAM ON TBE capable of satisfying that attraction if the base presented to it have a weaker attraction for carbonic acid than the potassa has. (85). 15.3 grns. of glassy boracic acid were fused over the gas-blowpipe with 37.7 grns. (1.246 eq. for each eq. of BO,) of fused carbonate of potassa for fifteen minutes weighed and again ignited for five minutes when a further loss of only 0.02 gm.had occurred. The carbonic acid expelled amounted to 10.39 grns or 1-07eq. for each eq. of BO,. 14.05 gms. of pure fused carbonate of soda (0.60eq. for 1 eq. BO,) were then added and the crucible again heated for ten minutes over the gas-blowpipe weighed (loss= 1.98 grns.) again heated for five minutes causing a further loss of 0-28gm. then a gain for five minutes when it lost only 0.1 grn. The carbonic acid expelled from the carbonate of soda by the boracic acid which had been already saturated with carbonate of 2otassa amounted to 2-20gms. or 0.227 eq. for each eq. of RO present. (86). A similar experiment with 7-12 gms. glassy boracic acid (1 eq.) and 18.14 gms. fused carbonate of potassa (1.28 eq.) Fiaal variation after five minutes ignition 0.02 grn.Carbonic acid expelled from the carbonate of potassa 4-86grns. or 1.08 eq. 17.40 grns. (1.60 eq.) of carbonate of soda added. Loss in fifteen minutes’ ignition 2-07grns. Final variation after five minutes’ iguition 0.04gm. Carbonic acid expelled from the carbonate of soda by the boracic acid already saturated with carbonate of potassa amounted to 2.11 grns. or 0.47 eq. for each eq. of BO,. (87). 8.72 grns. glassy boracic acid (1 eq.) 42.52 grns. fused carbonate of potassa (2.46 eqs.) Final variation in five minutes’ ignition 0.1 grn 12-04grns. more carbonate of potassa added. Further loss after fifteen minutes’ ignition 0.32.gm. Carbonic acid expelled from the carbonate of potassa 1-30 eq 17.48 grns. (1*32eq.) of fused carbonate of soda added.Loss in six minutes’ ignition 0.64 grn. Final variation in five minutes’ ignition 0.12 grn. ACTION OF BORACIC ACID &C. Carbonic acid expelled from the carbonate of soda by the boracic acid already saturated with carbonate of potassn amounted to 1-16 grn. or 0.21 eq. for each eq. BO,. (88.)1409 ps. of glassy boracic acid (1 eq.) 4753 grns fused carbonate of potassa (1.61eq.) Final variation after five minutes’ ignition 0.03 grn. 6.97 grns. more carbonate of potassa added. Further loss after ten minutes’ ignition 0-27gm. Final variation after five minutes’ ignition 0.00. Carbonic acid expelled from the carbonate of potassn 1.14 eq. 9.43 grns. (0-42eq.) of fixed carbonate of soda added. Loss in five minutes’ ignition 0.65 grn.Final variation in five minutes’ ignition 0°08 gm. Carbonic acid expelled from the carbonate of soda by boracic acid already saturated with carbonate of potassa 1*& ens. or 0.15 eq. for each eq. BO,. (89.) 10.02 grns. of glassy boracic acid (1eq.) 63.78 grns. of fused carbonate of potassa (3.2 eqs.) Final variation after five minutes’ igniton 0.05 grn. 6.58 grns. more carbonate of potassa added. Further loss after five minutes’ ignition 0.04 gm. Carbonic acid expelled from the carbonate of potassa 1.21 eqs. 11.57 grns. (076 eq.) of fused carbonate of soda added. Loss in five minutes’ ignition 0.63 grn. Final variation in five minutes’ ignition 0.12 grn. 5-98 grns. more carbonate of soda added. Further loss in five minutes’ ignition 0.24 grn.Added 3-03grns. more carbonate of soda. Further loss in five minutes’ ignition 0.28 grn. Final variation 0*10grn. Added 4-57 gms. more carbonate of soda. Final variation in five minutes’ ignition 0.17 grn. Carbonic acid expelled from the carbonate of soda by boracic acid already saturated with carbonate of potassa 1.84 grns. or 029 eq. for each eq. of boracic acid. Added 2.75 grns. (0.26 eq.) of carbonate of lithia. BLOXAM ON THE Loss in five minutes’ ignition 0.51 grn. Final variation 0.12gm. Total loss after adding the carbonate of lithia 1.15 grn. Deduct the maximum loss ever suffered by carbonate of lithia heated alone (15 per cent.) . . 0.41 ,, -Carbonic acid expelled . . 0.74 (0.11 eq.) from the carbonate of lithia by boracic acid already saturated with carbonate of potassa and carbonate of soda.(90.) 8.09 grns. glassy boracic acid (1 eq.) 64436 grns fused carbonate of potassa (3.6 eqs.) Final variation after seven minutes’ ignition 0.12 grn. 13.05 gms. more carbonate of potassa added. Further loss after five minutes’ ignition 0.07 grn. Carbonic acid expelled from the carbonate of potassa 3 026eqs. Added 6.47 gms. (0.69 eq.) of carbonate of lithia. Loss in five minutes’ ignition 1-33grns. Find variation 0.13 grn. Total loss after adding the carbonate of lithia 2-24 gms. Deduct the maximum loss ever. suffered by carbonate of lithia alone . . 097 ,’ -Carbonic acid expelled . . 1.27(0.136 eq.) from the carbonate of lithia by boracic acid already saturated with carbonate of posassa.(91.) 9.93 grns. glassy bonric acid (1 eq.) 81.42 grns. fused carbonate of soda (5.4eqs.) Final variation afker five minutes’ ignition 0.08 grn. 12.75 grns. more carbonate of soda added. Further loss in five minutes’ ignition 0.08 gm. Carbonic acid expelled from the carbonate of soda 2-31eqs. Added 4.46 gms. carbonate of lithia (0.42eq.) Loss in five minutes’ ignition 046 grn Final variation 0.17 grn . ACTION OF BORACIC ACID &C. Total loss after adding carbonate of lithia . 1.00 grn. Deduct maximum loss of carbonate of lithia alone . . 0.67 ,, -Carbonic acid expelled . . 0.33 (-031 eq,) from the carbonate of lithia by boracic acid already saturated with carbonate of soda.We are not surprised that the amount of carbonic acid expelled is in this case so small when we remember that 25 eqs. represent the average amount of carbonic acid expelled from carbonate of lithia by boracic acid and that as much as 2-31eqs. were here expelled from the cabonate of soda alone before any carbonate of lithia was added. It still remained to be seen whether boracic acid which had been saturated with carbonate of soda was not capable of expelling carbonic acid from carbonate of potassa. (92.)1414grns. glassy boracic acid (1 eq.) 43.25 griis. fused carbonate of soda (2-01eqs.) Final variation afier five minutes’ ignition 0.05 grn. Carbonic acid expelled from the carbonate of soda 1.79 eqs. Added 31.51 grns.of fused carbonate of potassa. Instead of suffering any furtber loss the mass now actually gained 005 gm. in five minutes’ ignition; it was then heated for ten minutes when it had gained 0.07 grn. in addition and on again heating for five minutes it had still gained 0.05 grn. This result is the more satisfactory because the boracic acid had not expelled from the carbonate of soda the greatest amount of carbonic acid which it is capableof displacing and still it refused to expel any carbonic acid from the carbonate of potassa. (93.) 16-OPgrns. glassy boracic acid (1eq.) 55-51gms. fused carbonate of soda (2.4eqs.) Final variation after five minutes’ ignition 0.09gn. Carbonic acid expelled from carbonate of soda 3-86 eqs. Added 21.3 grns. fused carbonate of potassa.Further loss in fifteen minutes’ ignition 0.2 grn. ‘it is evident therefore that boracic acid which has been saturated BLOXAM ON THE with carbonate of soda has no longer any tendency to expel carbonic acid from carbonate of potassa. It appeared probable that silicic acid would be found to behave with the two alkaline carbonates in the same manner as boracic acid. (94.) 9.52 gms. (1eq.*) of precipitated silicic acid were fused over the gas-blowpipe with 46.75 ens. (2.15eqs.) of fused car- bonate of potassa till a loss of only 004 grn. was observed after five minutes’ ignition the crucible was then placed for ten minutes in a very hot muffle when it only lost 0-13 grn. The carbonic acid expelled amounted to 6.63 gms.or 0.95 equivalent for each equi- valent of silicic acid. (95.) 9-84gms. (1eq.) of silicic acid. 57.80 grns. (2.57eqs.) fused carbonate of potassa. Final variation after five minutes’ ignition 0.06. grn. Carbonic acid expelled 6.68 grns. or 0.93 eq. Added 29.17 grns. hsed carbonate of soda. Loss in five minutes’ ignition 0.79 gm. Total loss after eighteen minutes 1.21grn. (0.17eq.) of carbonic acid expelled from carbonate of soda by silicic acid already saturated with carbonate of potasaa. (96.) 10.57 grns. (1 eq.) of finely powdered rock crystal fused with 66-83grns. (2.77 eqs.) of fused carbonate of potassa. Final variation in five minutes’ ignition 0.05 gm. Carbonic acid expelled 6.96 grns. (0.9eq.) Added 18.86 grns. fused carbonate of soda.Loss in five minutes’ ignition 0.28 grn. Total carbonic acid 0.55 gm. (0.07 eq.) expelled by the silicic acid already saturated with carbonate of potassa. (97.) 9-68 ens. (1 eq.) precipitated silica and 39-60gms. (2.03eqs.) pure carbonate of soda intimately mixed. Heated to dull redness till nearly constant in weight had lost 4.87 gms. (0.69eq.) of carbonic acid. * The equivalent weight of silicic acid is here taken a 80.24 (Si02). ACTION OF BORAClC ACID &C. Heated for fifteen minutes over gas-blowpipe had lost 9.09 grns. (1.30 eq.) Heated for ten minutes in hot muffle had lost 9.79 grns. (1.39 eq.) (98.) 9.31 gms. (1eq.) precipitated silica. 34.06 gms. (2.12eqs.) carbonate of soda Heated over gas-blowpipe till nearly constant had lost 9.24 gms.(1-36eq.) of carbonic acid. (99.) 10.4 grns. (1 eq.) precipitated silica. 35.34 grna. (1.93 eq.) fused carbonate of soda. Final variation in five minutes' ignition. 0.03 gm. Carbonic acid expelled 9-92 gms. (1.31eq,) Added 47-16grns. fused carbonate of potassa and again fused. After five minutes' fusion the mass had actually gained 01 gm. (100.) 6.89 grns. (1 eq.) of rock crystal. 45.93 (2.6 eqs.) fused carbonate of soda. Final variation in five minutes' ignition 0.1 gm. Carbonic acid expelled 9.68 grns. (1.34 eq.) Added 15.28 grns. fused carbonate of potassa and again fused. Gain iu five minutes' ignition 0.17 grn, '' in other five minutes 0°08 , Final variation in five minutes 0.00 , It is evident from these results that no carbonic acid can be expelled from carbonate of potassa by silicic acid already saturated with carbonate of soda.The conclusion deducible from these few experiments upon the action of silicic acid on the alkaline carbonates at high tempera- tures agrees pretty well with that furnished by the experiments of Col. Yorke who found that 1 eq. (30.24)of silicic acid expelled 0.97 eq. of carbonic acid from carbonate of potassa and 1-42eq. from carbonate of soda. I found 0.926 expelled from carbonate of potassa and 1.35 from carbonate of soda. It was also much easier to obtain a constant weight with carbonate of potassa and the results exhibited less variation. Further experiments upon the expulsion of other acids from their salts by boracic and silicic acids appear to be required before _we can safely infer that the attraction of boracic acid SCHUNCR ON THE for bases at high temperatures ia really greater than that of silicic acid.It would appear that in all attempts to determine the equivalent of an acid by the amount of carbonic acid displaced by it at high temperatures it would be safer to employ carbonate of potassa than carbonate of soda since the latter in the case of the two acids here examined has yielded far less constant results. On comparing the action of boracic acid upon carbowate of potassa at a bright red heat with that of silicic acid I am led to the belief that if the equivalent of the former acid be taken as = 349 (BO,) then the equivalent of silicic acid must be that which corrcsponds to the formula SiO,.