Page:Encyclopædia Britannica, Ninth Edition, v. 12.djvu/556

540 540 HYDROMETER it is U. P.). By applying the several weights in succession in addition to No. 4, the instrument can be employed for liquids heavier than water ; and graduations on the other three sides of the stem, together with an additional slide rule, adapt the instru ment for the determination of the strength of worts. Mr Atkins subsequently modified the instrument (Nicholson s Journal, 8vo, vol. iii. p. 50) by constructing the different weights of different shapes, viz., circular, square, triangular, and pentagonal, instead of numbering them 1, 2, 3 and 4 respectively, a figure of the weight being stamped on the sliding rule opposite to every letter in the series to which it belongs, thus diminishing the probability of mistakes. He also replaced the letters on the stem by the corre sponding specific gravities referred to water as unity. Further information concerning these instruments and the state of hydro- metry in 1803 will be found in Mr Atkins s pamphlet On the Relation between the Specific Gravities and the Strength of Spirituous Liquors, 1803 ; or Phil. Mag., vol. xvi. pp. 26-33, 205-212, 305- 312 ; vol. xvii. pp. 204-210 and 329-341. In Gay Lussac s alcoholometer the scale is divided into 100 parts corresponding to the presence of 1, 2, . . . per cent, by volume of alcohol at 15 C., the highest division of the scale corresponding to the purest alcohol he could obtain (density 7947) and the lowest division corresponding to pure water. A table provides the necessary corrections for other temperatures. Tralles s hydrometer differs from Gay Lussac s only in being graduated at 4 C. instead of 15 C., and taking alcohol of density 7939 at 15 5 C. for pure alcohol instead of 7947 as taken by Gay Lussac (Keene s Handbook of Hydrometry). In Beck s hydrometer the zero of the scale corresponds to density I OOO and the division 30 to density 850, and equal divisions on the scale are continued as far as is required in both directions. The following table serves to indicate the relation between the degrees and the corresponding densities : Relation between Degrees of Beck s Hydrometer and Densities. Degrees. i Density. Degrees. Density. Degrees. Density. Greater than 1-000. Less than 1-000. Greater than 1-000. Less than 1-000. Greater than 1-000. Less than 1-000. 1 1-006 994 25 1-172 872 48 1-393 780 2 1-012 988 26 1-181 867 49 1-405 776 3 1-018 983 27 1-189 863 50 1-417 773 4 1-024 977 28 1-197 859 51 1-429 769 5 1-030 971 29 1-206 854 52 1-441 766 6 1-037 966 30 1-214 850 53 1-453 762 7 1-043 960 31 1 -223 846 54 1-466 759 8 1-049 955 32 1-232 842 55 1-478 756 9 1-056 950 33 1-241 837 56 1-491 752 10 1-063 944 34 1-250 833 57 1-504 749 11 1-069 939 35 1-259 829 58 1-518 746 12 1-076 934 36 1-268 825 59 1-532 742 13 1-083 929 37 1-278 821 60 1-546 739 14 1-090 924 38 1-288 817 61 1-560 736 15 1-097 919 39 1-298 813 62 1-574 733 16 1-104 914 40 1-308 810 63 1-589 730 17 1-111 909 41 1-318 806 64 1-604 727 18 1-118 904 42 1-328 802 65 1-619 723 19 1-126 899 43 1-339 798 66 1-635 720 20 1-133 895 44 1-349 794 67 1 -651 717 21 1-141 890 45 1-360 791 68 1-667 714 22 1-149 885 46 1-371 787 69 1-683 711 23 1-157 881 47 1-382 783 70 1-700 708 24 1-164 876 In the centesimal hydrometer of M. Francceur the volume of the stem between successive divisions of the scale is always T ^th of the whole volume immersed when the instrument floats in water at 4 C. In order to graduate the stem the instrument is first weighed, then immersed in distilled water at 4 C., and the line of flotation marked zero. The first degree is then found by placing on the top of the stem a weight equal to y^h of the weight of the instrument, which increases the volume immersed by T -J-jjth of the original volume. The addition to the top of the stem of successive weights, each i^ T th of the weight of the instrument itself, serves to determine the successive degrees. The length of 100 divisions of the scale, or the length of the uniform stem the volume of which would be equal to that of the hydrometer up to the zero gradiiation, Fran cceur called the &quot;modulus&quot; of the hydrometer. He constructed his instruments of glass, using different instruments for different portions of the scale (Francceur, Traite d areometrie, Paris, 1842). Dr Bories of Montpellier constructed an hydrometer which was based upon the results of his experiments on mixtures of alcohol and water. The interval between the points corresponding to pure alcohol and to pure water Bories divided into 100 equal parts, though the stem was prolonged so as to contain, only 10 of these divisions, the other 90 being provided for by the addition of 9 weights to the bottom of the instrument as in Clarke s hydrometer. Sikes s hydrometer, on account of its similarity to that of Bories, appears to have been borrowed from that instrument. It is made of brass, and consists of a spherical ball A (fig. 9), : , 1 5 inches in diameter, below which is a weight B connected with the ball by a short conical stem C. The stem D is rectangular in section, and about 3| inches in length. This is divided into ten equal parts, each of which is subdivided into five. As in Bories s instrument, a series of 9 weights, each of the form shown at E, serves to extend the scale to 100 principal divisions. In the centre of each weight is a hole capable of admitting the lowest and thickest end of the conical stem C, and a slot is cut into it just wide enough to allow the upper part of the cone to pass. Each weight can thus be dropped on to the lower stem so as to rest on the counter poise B. The weights are marked 10, 20,. . . .90; and in using tiie instrument that weight must be selected which will allow it to float in the liquid with a portion only of the stem submerged. Then the reading of the scale at the line of flotation, added to the number on the weight, gives the reading required. A small supernumerary weight F is added, which can be placed upon the top of the stem. F is so adjusted that when the 60 weight is placed on the lower stem the instrument sinks to , the same point in distilled water when F is attached * ^, , as in proof spirit when F is removed. Hydrometer. The following table gives the specific gravities corresponding to the principal graduations on Sikes s hydrometer at 60 F. and at 62 F., together with the corresponding strengths of spirits. The latter are based upon the tables of Gilpin, for which the reader is referred to the Phil. Trans, for 1794. Table showing the Densities corresponding to the Indications of Sikes s Hydrometer. Sikes s Indications. 60 F. 62 F. Sikes s Indications. 60 F. 62 F. 3en^ity. Proof Spirit pei- cent. Density. Proof Spirit pei- cent. Density. Proof Spirit pei- cent. Density. Proof Spirit per cent.

815297 167-0 815400 166-5 51 905024 111-4 905138 110-7 1 816956 166-1 8170i9 165-6 52 906869 110-0 906983 109-3 2 818621 165-3 818725 164-8 53 908722 108-6 908837 107-9 3 820294 164-5 820397 163-9 54 910582 107-1 910697 106-5 4 821973 163-6 822077 I 163-1 55 912450 105-6 912565 305-0 5 823659 162-7 823763 | 162-3 56 914326 104-2 914441 103-5 6 825352 161-8
 * 825457 | 161-4

57 916209 102-7 91(323 102-0 7 827052 160-9 827157 | 160-5 58 918100 101-3 918216 100-5 8 828759 160-0 828864 1596 59 919999 99-7 920115 98-9 9 830473 159-1 830578 158-7 60 921906 98-1 922022 97-4 10 832195 158-2 832300 157-8 60u 921884 98-1 922000 97-4 11 833888 157-3 833993 156-8 61 923760 96-6 923877 95-9 12 835587 156-4 835692 155-9 62 925643 95-0 925760 94-2 13 837294 155-5 8374&amp;lt;;0 155-0 63 927534 93-3 927652 92-6 14 839008 154-6 839114 154-0 64 929433 91-7 929550 90-9 15 840729 153-7 840835 153-1 65 931339 90-0 931457 89-2 16 842458 152-7 842564 152-1 66 933254 88-3 933372 87-5 17 844193 151-7 844299 151-1 67 935176 86-5 935294 85-8 18 845936 150-7 84C042 150-1 68 937107 84-7 937225 84-0 19 847685 149-7 847792 149-1 69 939045 82-9 939163 82-2 20 849442 148-7 849549 | 148-1 70 940991 81-1 941110 80-3 20u 849393 148-7 849500 1 148-1 70a 940981 81-1 941100 80-3 21 851122 147-6 851229 1471 71 942897 79-2 943016 78-4 22 852857 146-6 852964 146-1 72 944819 77-3 944938 76-5 23 854599 145-6 854707 145-1 73 946749 75-3 946869 74-5 24 856348 144-6 856456 144-0 74 948687 73-3 9488Q7 72-5 25 858105 143-5 858213 142-9 75 950634 71-2 950753 70-4 26 859S69 142-4 859978 141-8 76 952588 69-0 952708 68-2 27 861640 141-3 861749 1408 77 954550 66-8 954670 66-0 28 863419 140-2 863528 1397 78 956520 64-4 956641 63-5 29 865201 139-1 865313 1385 79 958498 61-9 958619 61-1 30 866998 138-0 867107 137-4 80 960485 59-4 960006 58-5 30u 866991 138-0 867100 137-4 80n 960479 59-4 960600 58-5 31 868755 136-9 868865 136-2 81 962433 56-7 962555 55-8 32 870526 135-7 870636 135-1 82 964395 53-9 964517 53-0 33 872305 134-5 872415 133-9 83 966366 50-9 9H6488 50-0 34 874090 133-4 874200 1328 84 9C8344 47-8 968466 47-0 35 875883 132-2 875994 131-6 85 970331 44-5 970453 43-8 36 877684 131-0 877995 130-4 86 972325 41-0 972448 40-4 37 879492 129-8 879603 129-1 87 974328 37-5 974451 36-9 38 881307 128-5 881419 127-9 88 976340 34-0 976463 33-5 39 883129 127-3 883241 126-7 89 978359 30-6 978482 30-1 40 884960 126-0 885072 125-4 90 980386 27-2 980510 26-7 40u 884888 126-0 885000 125-4 90u 980376 27-2 980500 26-7 41 886689 124-8 886801 124-2 91 982871 23-9 982496 23-6 42 888497 123-5 888609 122-9 92 984374 20-8 984498 205 43 890312 122-2 81)0425 121 fi 93 986385 17-7 986510 17-4 44 892135 120-9 892248 120-3 94 988404 14-8 988529 14-5 45 893965 1196 894078 119-0 95 990431 12-0 990557 11-7 46 895803 118-3 895916 1176 96 992468 9-3 992593 9-0 47 897G47 116-9 897761 1163 97 994512 6-7 994637 6-5 48 899.500 115-6 899614 1149 98 996565 4-1 996691 40 49 901360 1142 901417 113-5 99 998626 1-8 998752 1-6 50 903229 1128 903343 112-1 100 1-000696 o-o 1-000822 o-o 50s 903186 1128 903300 112-1 -