20 BULLETIN 897, U. S. DEPARTMENT OF AGRICULTURE. 
SUMMARY. 
1. The following specifications have been selected to represent good 
commercial practice in packaging granular, solid, free-flowing food 
products: 
_ 1. That packages of 5 pounds and below be weighed net; larger packages may 
be weighed gross and tare. - 
2. That the following types of scale be used— 
For packages of 5 pounds and below: Even arm balance, 1-pound beam, 4- 
ounce graduation. 
For packages over 5 and under 25 pounds: Even arm balance, 2-pound 
beam, t-ounce graduation. 
For packages of 25 pounds and above: Platform scale, 50-pound beam, 4- 
pound graduation. 
3. That scales meet the tolerances prescribed in Bureau of Standards Circular 
61 and be used at 20 per cent or more of their capacity for packages of less than 
25 pounds and at 10 per cent or more of their capacity for larger packages. Tare 
weights may be made on the same scale as the gross weights. 
4. That the exact balance be estimated to within one-half of the sensibility 
reciprocal of the scale and the poise be set to within one-fourth of the minimum 
graduation on the beam. 
2. The maximum errors of good commercial practice given in Table 
15 have been calculated by the use of methods of least squares, the 
Bureau of Standards tolerances on scales, and the specifications of 
good commercial practice. 
, 
TaBLE 15.—Calculated maximum errors of good commercial practice. 

For gross and tare 
| For net weighing. weighing 
Size of package. \ On the On the 
: average + la| average 
Onsitek ofarepre- SRS Ee ofarepre- 
Packases.:| sentative | PACS@8°S-| sentative 
sample. sample. 

Ounces. | Ounces. | Ounces. | Ounces. 


2-OUN COR 2. cree = seiner aciere 0.150 Ql09 72 | eaee st aee leceesesace 
S-OUNCE Saat ane sae oe eee - 150 OO72" |): SRE ane Shee 
AQUI CO mei eater me Eee - 150 WS ieeel ieaererse Sen eta seisesec 
S“QUINCE A ae Sees eee nee . 150 O97 A\hete eae | See Sek oe 
1=pound = = pea as ase 213 LOGON ae Bee leceee lowes 
2-POUNG2 22 ae ees so 8 ae eee 360 145: 02 Seen eee eee 
Se POUL Se eee See ee aa 363 TU Fal PRS ty UN ere 
4-DOUN OHNE ea a: See eee oe 409 lees aco oassedisoodccance 
SOLO PHAYO LE See Jt eee sees - 409 20D il orators Sea 
1O=poundiee aa see nae nee -544 | 373 0.674 0.414 
25-POUN CE ree ae see seer 5.41 2.68 7.49 3.34 
HO-POUNGAa ke eee Ue aaa 5.41 2.68 To TS: SOL 
(5-POUN Gees asta ee ee 5.65 2.92 Ueda le ee BY 
100-pound and above...-..... 5.65 2.92 8:29 |. 4293 



3. A study of machine weighing has removed practically all doubts 
of the ability of properly operated machines to meet the calculated 
maximum errors of hand weighing. 
4. Data have been collected which show that the calculated maxi- 
mum errors represent a close approximation to the maximum Varia- 
tions of good commercial practice. 
WASHINGTON : GOVEKNMENT PRINTING OFFICE : 1929 
Ss. 
t 


